Jan. 12 (Bloomberg) -- Greek and U.S. authorities started investigating a rocket attack on the American Embassy in Athens this morning, police said. The blast caused minor damage and there were no injuries.

The explosion, at 5.58 a.m. this morning, was caused by a rocket fired from outside the Embassy compound, according to a statement from the Greek Public Order Ministry, posted on its Web site. The area was immediately cordoned off. Investigations have begun into the cause of the blast.

``This is a very serious attack,'' U.S. Ambassador Charles Ries said in comments to reporters outside the building, which is located in central Athens on Vasillissis Sophias Avenue.

Greek Foreign Minister Dora Bakoyannis said it was too early to draw conclusions about who was behind the attack.

To contact the reporter on this story: Maria Petrakis in Athens at mpetrakis@bloomberg.net

Last Updated: January 12, 2007 02:16 EST