diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index 47bd9a7..54bb1b8 100644
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -1060,6 +1060,10 @@
         self.mode = {"r": "rb", "a": "r+b", "w": "wb"}[mode]
 
         if not fileobj:
+            if self._mode == "a" and not os.path.exists(self.name):
+                # Create nonexistent files in append mode.
+                self._mode = "w"
+                self.mode = "wb"
             fileobj = file(self.name, self.mode)
             self._extfileobj = False
         else:
@@ -1093,7 +1097,8 @@
                     self.fileobj.seek(0)
                     break
                 if tarinfo is None:
-                    self.fileobj.seek(- BLOCKSIZE, 1)
+                    if self.offset > 0:
+                        self.fileobj.seek(- BLOCKSIZE, 1)
                     break
 
         if self._mode in "aw":
@@ -1120,7 +1125,7 @@
            'r:'         open for reading exclusively uncompressed
            'r:gz'       open for reading with gzip compression
            'r:bz2'      open for reading with bzip2 compression
-           'a' or 'a:'  open for appending
+           'a' or 'a:'  open for appending, creating the file if necessary
            'w' or 'w:'  open for writing without compression
            'w:gz'       open for writing with gzip compression
            'w:bz2'      open for writing with bzip2 compression
diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
index 1674594..642f376 100644
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -305,6 +305,61 @@
         self.assertEqual(self.dst.getnames(), [], "added the archive to itself")
 
 
+class AppendTest(unittest.TestCase):
+    # Test append mode (cp. patch #1652681).
+
+    def setUp(self):
+        self.tarname = tmpname()
+        if os.path.exists(self.tarname):
+            os.remove(self.tarname)
+
+    def _add_testfile(self, fileobj=None):
+        tar = tarfile.open(self.tarname, "a", fileobj=fileobj)
+        tar.addfile(tarfile.TarInfo("bar"))
+        tar.close()
+
+    def _create_testtar(self):
+        src = tarfile.open(tarname())
+        t = src.getmember("0-REGTYPE")
+        t.name = "foo"
+        f = src.extractfile(t)
+        tar = tarfile.open(self.tarname, "w")
+        tar.addfile(t, f)
+        tar.close()
+
+    def _test(self, names=["bar"], fileobj=None):
+        tar = tarfile.open(self.tarname, fileobj=fileobj)
+        self.assert_(tar.getnames() == names)
+
+    def test_non_existing(self):
+        self._add_testfile()
+        self._test()
+
+    def test_empty(self):
+        open(self.tarname, "w").close()
+        self._add_testfile()
+        self._test()
+
+    def test_empty_fileobj(self):
+        fobj = StringIO.StringIO()
+        self._add_testfile(fobj)
+        fobj.seek(0)
+        self._test(fileobj=fobj)
+
+    def test_fileobj(self):
+        self._create_testtar()
+        data = open(self.tarname).read()
+        fobj = StringIO.StringIO(data)
+        self._add_testfile(fobj)
+        fobj.seek(0)
+        self._test(names=["foo", "bar"], fileobj=fobj)
+
+    def test_existing(self):
+        self._create_testtar()
+        self._add_testfile()
+        self._test(names=["foo", "bar"])
+
+
 class Write100Test(BaseTest):
     # The name field in a tar header stores strings of at most 100 chars.
     # If a string is shorter than 100 chars it has to be padded with '\0',
@@ -711,6 +766,7 @@
         ReadAsteriskTest,
         ReadStreamAsteriskTest,
         WriteTest,
+        AppendTest,
         Write100Test,
         WriteSize0Test,
         WriteStreamTest,