diff --git a/src/BOPTest/BOPTest_BOPCommands.cxx b/src/BOPTest/BOPTest_BOPCommands.cxx
index 068c2cb90b..b7bc787e9b 100644
--- a/src/BOPTest/BOPTest_BOPCommands.cxx
+++ b/src/BOPTest/BOPTest_BOPCommands.cxx
@@ -104,7 +104,7 @@ static Standard_Integer mkvolume   (Draw_Interpretor&, Standard_Integer, const c
   theCommands.Add("bsection", "use bsection r s1 s2 [-n2d/-n2d1/-n2d2] [-na]", 
                                                       __FILE__, bsection, g);
   //
-  theCommands.Add("bopcurves", "use bopcurves F1 F2 [-2d/-2d1/-2d2]",
+  theCommands.Add("bopcurves", "use bopcurves F1 F2 [-2d/-2d1/-2d2] [-p u1 v1 u2 v2]",
                                                       __FILE__, bopcurves, g);
   theCommands.Add("mkvolume", "make solids from set of shapes.\nmkvolume r b1 b2 ... [-c] [-ni]", 
                   __FILE__, mkvolume , g);
@@ -562,29 +562,44 @@ Standard_Integer bopcurves (Draw_Interpretor& di,
   Standard_Boolean aToApproxC3d, aToApproxC2dOnS1, aToApproxC2dOnS2, anIsDone;
   Standard_Integer i, aNbCurves, aNbPoints;
   Standard_Real anAppTol, aTolR;
+  IntSurf_ListOfPntOn2S aListOfPnts;
   TCollection_AsciiString aNm("c_"), aNp("p_");
   //
   anAppTol = 0.0000001;
   aToApproxC3d = Standard_True;
   aToApproxC2dOnS1 = Standard_False;
   aToApproxC2dOnS2 = Standard_False;
+
   //
-  if (n > 3) {
-    if (!strcasecmp(a[3],"-2d")) {
+  for(Standard_Integer i = 3; i < n; i++)
+  {
+    if (!strcasecmp(a[i],"-2d")) {
       aToApproxC2dOnS1 = Standard_True;
       aToApproxC2dOnS2 = Standard_True;
     } 
-    else if (!strcasecmp(a[3],"-2d1")) {
+    else if (!strcasecmp(a[i],"-2d1")) {
       aToApproxC2dOnS1 = Standard_True;
     }
-    else if (!strcasecmp(a[3],"-2d2")) {
+    else if (!strcasecmp(a[i],"-2d2")) {
       aToApproxC2dOnS2 = Standard_True;
     }
+    else if (!strcasecmp(a[i],"-p")) {
+      IntSurf_PntOn2S aPt;
+      const Standard_Real aU1 = Draw::Atof(a[++i]);
+      const Standard_Real aV1 = Draw::Atof(a[++i]);
+      const Standard_Real aU2 = Draw::Atof(a[++i]);
+      const Standard_Real aV2 = Draw::Atof(a[++i]);
+
+      aPt.SetValue(aU1, aV1, aU2, aV2);
+      aListOfPnts.Append(aPt);
+    }
     else {
-      di << "Wrong key. To build 2d curves use: bopcurves F1 F2 -2d/-2d1/-2d2 \n";
+      di << "Wrong key. To build 2d curves use: bopcurves F1 F2 [-2d/-2d1/-2d2] [-p u1 v1 u2 v2]\n";
       return 1;
     }
+
   }
+
   //
   IntTools_FaceFace aFF;
   //
@@ -592,6 +607,7 @@ Standard_Integer bopcurves (Draw_Interpretor& di,
                      aToApproxC2dOnS1,
                      aToApproxC2dOnS2,
                      anAppTol);
+  aFF.SetList(aListOfPnts);
   //
   aFF.Perform (aF1, aF2);
   //
diff --git a/src/IntPatch/IntPatch_WLineTool.cxx b/src/IntPatch/IntPatch_WLineTool.cxx
index 02208c1f68..49d8635eae 100644
--- a/src/IntPatch/IntPatch_WLineTool.cxx
+++ b/src/IntPatch/IntPatch_WLineTool.cxx
@@ -448,8 +448,9 @@ static Handle(IntPatch_WLine)
       Standard_Integer aHashIdx = 
         Standard_Integer(anIdx * theWLine->NbPnts() / 9);
 
-      //Store this point.
-      aNewPointsHash(aHashIdx) = 0;
+      //Vertex must be stored as VERTEX (HASH = -1)
+      if (aNewPointsHash(aHashIdx) != -1)
+        aNewPointsHash(aHashIdx) = 0;
     }
   }
 
diff --git a/src/IntTools/IntTools_FaceFace.cxx b/src/IntTools/IntTools_FaceFace.cxx
index 2ad7420f69..c309e91d27 100644
--- a/src/IntTools/IntTools_FaceFace.cxx
+++ b/src/IntTools/IntTools_FaceFace.cxx
@@ -875,9 +875,9 @@ void IntTools_FaceFace::MakeCurve(const Standard_Integer Index,
     L = aWLine;
 
     //
-    if(!myListOfPnts.IsEmpty()) {
-      bAvoidLineConstructor = Standard_True;
-    }
+    //if(!myListOfPnts.IsEmpty()) {
+    //  bAvoidLineConstructor = Standard_True;
+    //}
 
     Standard_Integer nbp = aWLine->NbPnts();
     const IntSurf_PntOn2S& p1 = aWLine->Point(1);
diff --git a/tests/boolean/bsection/M3 b/tests/boolean/bsection/M3
index fa0d8193d5..458d847759 100644
--- a/tests/boolean/bsection/M3
+++ b/tests/boolean/bsection/M3
@@ -1,8 +1,47 @@
-puts "TODO #OCC26777 ALL: Error : The length of result shape is"
-
 restore [locate_data_file GEN758_nofog.rle] a
-explode a
+explode a f
+
+# see issue #26777
+set GoodNbCurv 1
+
+set log [bopcurves a_1 a_2 -2d -p 0.20639206339545224 0.69260832843385300 0.0 0.017002507022347624]
+regexp {Tolerance Reached=+([-0-9.+eE]+)\n+([-0-9.+eE]+)} ${log} full Tolerance_Reached NbCurv
+
+set expected_Tolerance_Reached 2.2797192759881918e-005
+set tol_abs_Tolerance_Reached 0.0
+set tol_rel_Tolerance_Reached 1.0e-2
+checkreal "Tolerance Reached" ${Tolerance_Reached} ${expected_Tolerance_Reached} ${tol_abs_Tolerance_Reached} ${tol_rel_Tolerance_Reached}
+
+if {${NbCurv} != ${GoodNbCurv}} {
+  puts "Error: ${GoodNbCurv} curves are expected but ${NbCurv} are found!"
+}
+
+smallview
+clear
+
+if {${NbCurv} == 1} {
+  display c_1
+  fit
+} else {
+  for { set i 1 } { ${i} <= ${NbCurv} } {incr i} {
+    bounds c_$i u1 u2
+    cvalue c_$i u2 xx yy zz
+    point p$i xx yy zz
+  }
+  
+  fit
+  
+  for { set i 1 } { ${i} <= ${NbCurv} } {incr i} {
+    erase p$i
+    display c_$i
+  }
+}
+
+xwd ${imagedir}/${casename}_curv.png
+
+donly a_1 a_2
+
 bsection result a_1 a_2
 
 checkprops result -l 22.2575
-checksection result
+checksection result
\ No newline at end of file
diff --git a/tests/bugs/modalg_6/bug26841_1 b/tests/bugs/modalg_6/bug26841_1
new file mode 100644
index 0000000000..48c57e89ce
--- /dev/null
+++ b/tests/bugs/modalg_6/bug26841_1
@@ -0,0 +1,50 @@
+puts "============"
+puts "OCC26841"
+puts "============"
+puts ""
+###############################
+## Wrong result obtained by intersection algorithm.
+###############################
+
+restore [locate_data_file bug26841c1-prism.brep] p1
+restore [locate_data_file bug26841c1-deck.brep] a1
+
+bsection result a1 p1 -n2d2
+
+smallview
+donly result
+fit
+display a1 p1
+
+set nbshapes_expected "
+Number of shapes in shape
+ VERTEX    : 5
+ EDGE      : 5
+ WIRE      : 0
+ FACE      : 0
+ SHELL     : 0
+ SOLID     : 0
+ COMPSOLID : 0
+ COMPOUND  : 1
+ SHAPE     : 11
+"
+
+checknbshapes result -ref ${nbshapes_expected} -t -m "SECTION"
+
+regexp {Tolerance +MAX=([-0-9.+eE]+)} [tolerance result] full MaxTolerance
+puts "MaxTolerance=$MaxTolerance"
+
+set expected_MaxTolerance 4.8861509475438473e-005
+set tol_abs_MaxTolerance 0.0
+set tol_rel_MaxTolerance 0.01
+checkreal "MaxTolerance" ${MaxTolerance} ${expected_MaxTolerance} ${tol_abs_MaxTolerance} ${tol_rel_MaxTolerance}
+
+set log [checksection result]
+
+if { [string compare -nocase $log " nb alone Vertices : 0\n\n"] } {
+  puts "ERROR: the section is not closed"
+} else {
+  puts "The section is OK"
+}
+
+set only_screen_axo 1
\ No newline at end of file
diff --git a/tests/bugs/modalg_6/bug26841_2 b/tests/bugs/modalg_6/bug26841_2
new file mode 100644
index 0000000000..591aec9400
--- /dev/null
+++ b/tests/bugs/modalg_6/bug26841_2
@@ -0,0 +1,51 @@
+puts "============"
+puts "OCC26841"
+puts "============"
+puts ""
+###############################
+## Wrong result obtained by intersection algorithm.
+###############################
+
+restore [locate_data_file bug26841c3-prism.brep] p3
+restore [locate_data_file bug26841c3-deck.brep] a3
+
+bsection result a3 p3 -n2d2
+
+smallview
+donly result
+fit
+display a3 p3
+
+
+set nbshapes_expected "
+Number of shapes in shape
+ VERTEX    : 10
+ EDGE      : 10
+ WIRE      : 0
+ FACE      : 0
+ SHELL     : 0
+ SOLID     : 0
+ COMPSOLID : 0
+ COMPOUND  : 1
+ SHAPE     : 21
+"
+
+checknbshapes result -ref ${nbshapes_expected} -t -m "SECTION"
+
+regexp {Tolerance +MAX=([-0-9.+eE]+)} [tolerance result] full MaxTolerance
+puts "MaxTolerance=$MaxTolerance"
+
+set expected_MaxTolerance 0.00010145423883977269
+set tol_abs_MaxTolerance 0.0
+set tol_rel_MaxTolerance 0.001
+checkreal "MaxTolerance" ${MaxTolerance} ${expected_MaxTolerance} ${tol_abs_MaxTolerance} ${tol_rel_MaxTolerance}
+
+set log [checksection result]
+
+if { [string compare -nocase $log " nb alone Vertices : 0\n\n"] } {
+  puts "ERROR: the section is not closed"
+} else {
+  puts "The section is OK"
+}
+
+set only_screen_axo 1
\ No newline at end of file