diff --git a/core/KaSa_rep/frontend/prepreprocess.ml b/core/KaSa_rep/frontend/prepreprocess.ml
index 8ffd8fbe6..02664127b 100644
--- a/core/KaSa_rep/frontend/prepreprocess.ml
+++ b/core/KaSa_rep/frontend/prepreprocess.ml
@@ -1008,4 +1008,5 @@ let translate_compil parameters error
       Ast.tokens = compil.Ast.tokens;
       Ast.volumes = compil.Ast.volumes;
       Ast.guard_param_values = compil.Ast.guard_param_values;
+      Ast.conflicts = compil.Ast.conflicts;
     } )
diff --git a/core/grammar/ast.ml b/core/grammar/ast.ml
index 5a7bad24f..9aeb9ea7e 100644
--- a/core/grammar/ast.ml
+++ b/core/grammar/ast.ml
@@ -166,6 +166,7 @@ type ('agent, 'agent_id, 'pattern, 'mixture, 'id, 'rule) instruction =
       * string LKappa.guard option
       * 'rule Loc.annoted)
   | GUARD_PARAM of (string Loc.annoted * bool)
+  | CONFLICT of (string Loc.annoted * string Loc.annoted * string Loc.annoted)
 
 type ('pattern, 'mixture, 'id, 'rule) command =
   | RUN of ('pattern, 'id) Alg_expr.bool Loc.annoted
@@ -192,6 +193,8 @@ type ('agent, 'agent_sig, 'pattern, 'mixture, 'id, 'rule) compil = {
   volumes: (string * float * string) list;
   guard_param_values: (string Loc.annoted * bool) list;
       (** The guard parameters that have a defined value (true or false).*)
+  conflicts: (string Loc.annoted * string Loc.annoted * string Loc.annoted) list;
+      (** A conflict (A, s1, s2) states that there might be a conflict between the two sites s1, s2 of the agent A.*)
 }
 
 type parsing_compil = (agent, agent_sig, mixture, mixture, string, rule) compil
@@ -234,6 +237,7 @@ let empty_compil =
     tokens = [];
     volumes = [];
     guard_param_values = [];
+    conflicts = [];
   }
 
 (*
@@ -1122,7 +1126,7 @@ let print_perturbation f ((alarm, cond, modif, rep), _) =
     rep
 
 let print_parsing_compil_kappa f c =
-  Format.fprintf f "@[<v>%a@,@,%a@,%a@,@,%a@,@,%a@,%a@,@,%a@,@,%a@,%a@,@]@."
+  Format.fprintf f "@[<v>%a@,@,%a@,%a@,@,%a@,@,%a@,%a@,@,%a@,@,%a@,%a@,%a@,@]@."
     (Pp.list Pp.space print_configuration)
     c.configurations
     (Pp.list Pp.space (fun f a ->
@@ -1153,6 +1157,9 @@ let print_parsing_compil_kappa f c =
     (Pp.list Pp.space (fun f ((s, _), b) ->
          Format.fprintf f "%%guard_param: %s -> %b" s b))
     c.guard_param_values
+    (Pp.list Pp.space (fun f ((a, _), (s1, _), (s2, _)) ->
+         Format.fprintf f "%%conflict: %s %s %s" a s1 s2))
+    c.conflicts
 
 let arrow_notation_to_yojson filenames f_mix f_var r =
   JsonUtil.smart_assoc
@@ -1738,6 +1745,13 @@ let compil_to_json c =
              (Loc.string_annoted_to_json ~filenames)
              JsonUtil.of_bool)
           c.guard_param_values );
+      ( "conflicts",
+        JsonUtil.of_list
+          (JsonUtil.of_triple
+             (Loc.string_annoted_to_json ~filenames)
+             (Loc.string_annoted_to_json ~filenames)
+             (Loc.string_annoted_to_json ~filenames))
+          c.conflicts );
     ]
 
 let compil_of_json = function
@@ -1843,6 +1857,17 @@ let compil_of_json = function
                      (JsonUtil.exn_msg_cant_import_from_json
                         "AST guard_param_values boolean value")))
              (List.assoc "guard_param_values" l);
+         conflicts =
+           JsonUtil.to_list
+             ~error_msg:
+               (JsonUtil.exn_msg_cant_import_from_json "AST conflicts sig")
+             (JsonUtil.to_triple
+                ~error_msg:
+                  (JsonUtil.exn_msg_cant_import_from_json "AST conflicts sig")
+                (Loc.string_annoted_of_json ~filenames)
+                (Loc.string_annoted_of_json ~filenames)
+                (Loc.string_annoted_of_json ~filenames))
+             (List.assoc "conflicts" l);
        }
      with Not_found ->
        raise (Yojson.Basic.Util.Type_error ("Incorrect AST", x)))
diff --git a/core/grammar/ast.mli b/core/grammar/ast.mli
index f55055d77..b12172499 100644
--- a/core/grammar/ast.mli
+++ b/core/grammar/ast.mli
@@ -145,6 +145,7 @@ type ('agent, 'agent_sig, 'pattern, 'mixture, 'id, 'rule) instruction =
       * string LKappa.guard option
       * 'rule Loc.annoted)
   | GUARD_PARAM of (string Loc.annoted * bool)
+  | CONFLICT of (string Loc.annoted * string Loc.annoted * string Loc.annoted)
 
 type ('pattern, 'mixture, 'id, 'rule) command =
   | RUN of ('pattern, 'id) Alg_expr.bool Loc.annoted
@@ -169,6 +170,7 @@ type ('agent, 'agent_sig, 'pattern, 'mixture, 'id, 'rule) compil = {
   tokens: string Loc.annoted list;
   volumes: (string * float * string) list;
   guard_param_values: (string Loc.annoted * bool) list;
+  conflicts: (string Loc.annoted * string Loc.annoted * string Loc.annoted) list;
 }
 
 type parsing_compil = (agent, agent_sig, mixture, mixture, string, rule) compil
diff --git a/core/grammar/cst.ml b/core/grammar/cst.ml
index 4f9d931c3..0501999bf 100644
--- a/core/grammar/cst.ml
+++ b/core/grammar/cst.ml
@@ -40,5 +40,7 @@ let append_to_ast_compil rev_instr compil =
         {
           r with
           Ast.guard_param_values = (params_sig, b) :: r.Ast.guard_param_values;
-        })
+        }
+      | Ast.CONFLICT (agent, site1, site2) ->
+        { r with Ast.conflicts = (agent, site1, site2) :: r.Ast.conflicts })
     compil (List.rev rev_instr)
diff --git a/core/grammar/kappaParser.mly b/core/grammar/kappaParser.mly
index f5a33b5e0..f6d33bed4 100644
--- a/core/grammar/kappaParser.mly
+++ b/core/grammar/kappaParser.mly
@@ -100,6 +100,9 @@ start_rule:
 		      | Ast.GUARD_PARAM (param_name,b) ->
           {r with
 			  Ast.guard_param_values = (param_name,b)::r.Ast.guard_param_values}
+          | Ast.CONFLICT (a,s1,s2) ->
+          {r with
+			  Ast.conflicts = (a,s1,s2)::r.Ast.conflicts}
 		  }
     | error
 	{raise (ExceptionDefn.Syntax_Error (add_pos "Syntax error"))}
diff --git a/core/grammar/klexer4.mll b/core/grammar/klexer4.mll
index 7d0ee64f4..b47c941d2 100644
--- a/core/grammar/klexer4.mll
+++ b/core/grammar/klexer4.mll
@@ -91,6 +91,7 @@ rule token = parse
     | "def" -> CONFIG
     | "token" -> TOKEN
     | "guard_param" -> GUARD_PARAM
+    | "conflict" -> CONFLICT
     | _ as s -> raise (ExceptionDefn.Syntax_Error
       ("Unknown directive: "^s,
        Loc.of_pos (Lexing.lexeme_start_p lexbuf)
diff --git a/core/grammar/kparser4.mly b/core/grammar/kparser4.mly
index 8d72a2b34..228805957 100644
--- a/core/grammar/kparser4.mly
+++ b/core/grammar/kparser4.mly
@@ -27,7 +27,7 @@
 %token SHARP UNDERSCORE PIPE RAR LRAR LAR EMAX TMAX CPUTIME TIME EVENT NULL_EVENT
 %token COLON NEWLINE BACKSLASH SIGNATURE TOKEN INIT OBS PLOT PERT CONFIG APPLY
 %token DELETE INTRO SNAPSHOT STOP FLUX TRACK ASSIGN PRINTF PLOTENTRY SPECIES_OF
-%token DO REPEAT ALARM RUN LET GUARD_PARAM SHARP_OP_BRA IF
+%token DO REPEAT ALARM RUN LET GUARD_PARAM SHARP_OP_BRA IF CONFLICT
 %token <int> INT
 %token <float> FLOAT
 %token <string> ID LABEL STRING
@@ -828,6 +828,7 @@ an algebraic expression is expected")) }
   | CONFIG annoted STRING annoted value_list
     { add (Ast.CONFIG (($3,rhs_pos 3),$5)) }
   | GUARD_PARAM annoted ID annoted boolean annoted { add (Ast.GUARD_PARAM (($3,rhs_pos 3), $5)) }
+  | CONFLICT annoted ID annoted ID annoted ID annoted { add (Ast.CONFLICT (($3,rhs_pos 3), ($5,rhs_pos 5), ($7,rhs_pos 7))) }
   ;
 
 model_body:
diff --git a/core/grammar/lKappa_compiler.ml b/core/grammar/lKappa_compiler.ml
index 0aca67018..9715c79a9 100644
--- a/core/grammar/lKappa_compiler.ml
+++ b/core/grammar/lKappa_compiler.ml
@@ -2766,5 +2766,6 @@ let compil_of_ast ~warning ~debug_mode ~syntax_version ~var_overwrite ast_compil
         signatures = ast_compil.signatures;
         configurations = ast_compil.configurations;
         guard_param_values = ast_compil.guard_param_values;
+        conflicts = ast_compil.conflicts;
       };
   }