diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -148,6 +148,8 @@
             break
     if not abortstate:
         raise error.Abort(_('no operation in progress'))
+    if abortstate._opname == 'merge':
+        return hg.merge(repo, abort=True)
     if abortstate._abortfunc:
         return abortstate._abortfunc(ui, repo)
     raise error.Abort((_("%s does not support 'hg abort'") %
diff --git a/mercurial/hg.py b/mercurial/hg.py
--- a/mercurial/hg.py
+++ b/mercurial/hg.py
@@ -952,8 +952,8 @@
 
     return ret
 
-def merge(repo, node, force=None, remind=True, mergeforce=False, labels=None,
-          abort=False):
+def merge(repo, node=None, force=None, remind=True, mergeforce=False,
+          labels=None, abort=False):
     """Branch merge with node, resolving changes. Return true if any
     unresolved conflicts."""
     if not abort:
diff --git a/tests/test-abort.t b/tests/test-abort.t
--- a/tests/test-abort.t
+++ b/tests/test-abort.t
@@ -628,9 +628,8 @@
 Unshelve abort fails with appropriate message if there's no unshelve in
 progress
   $ hg abort
-  abort: merge does not support 'hg abort'
-  (use 'hg commit' or 'hg merge --abort')
-  [255]
+  aborting the merge, updating back to 9451eaa6eee3
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ cd ..
 
 Abort due to pending changes
@@ -902,3 +901,59 @@
   $ hg abort
   abort: no operation in progress
   [255]
+  $ cd ..
+
+####TEST `hg abort` operation merge
+
+  $ addcommit () {
+  >     echo $1 > $1
+  >     hg add $1
+  >     hg commit -d "${2} 0" -m $1
+  > }
+
+  $ commit () {
+  >     hg commit -d "${2} 0" -m $1
+  > }
+
+  $ hg init a
+  $ cd a
+  $ addcommit "A" 0
+  $ addcommit "B" 1
+  $ echo "C" >> A
+  $ commit "C" 2
+
+  $ hg update -C 0
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ echo "D" >> A
+  $ commit "D" 3
+  created new head
+
+State before the merge
+
+  $ hg status
+  $ hg id
+  e45016d2b3d3 tip
+  $ hg summary
+  parent: 3:e45016d2b3d3 tip
+   D
+  branch: default
+  commit: (clean)
+  update: 2 new changesets, 2 branch heads (merge)
+  phases: 4 draft
+
+Testing the abort functionality first in case of conflicts
+
+  $ hg abort
+  abort: no operation in progress
+  [255]
+  $ hg merge
+  merging A
+  warning: conflicts while merging A! (edit, then use 'hg resolve --mark')
+  1 files updated, 0 files merged, 0 files removed, 1 files unresolved
+  use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
+  [1]
+
+  $ hg abort
+  aborting the merge, updating back to e45016d2b3d3
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+