WASHINGTON (AP) _ Marines and Navy commandos were rushed to the temporary location of the U.S. Embassy in Tirana, Albania, to increase security after U.S. officials learned of a possible terrorist attack, President Clinton said Tuesday.

In a letter notifying Congress of the situation, Clinton said that as of Monday all but 50 of the 200 Marines sent to Tirana on Sunday had returned to Navy ships in the Adriatic Sea that are participating in an amphibious NATO military exercise.

In addition to the Marines, a team of 10 Navy SEAL commandos was dispatched to the Rilindja Ridge housing complex in Tirana where U.S. Embassy business is being conducted until a more secure permanent embassy is built.

Clinton wrote that U.S. authorities had received ``credible information of a possible attack'' against the U.S. Embassy in Tirana ``similar to the attacks against our missions'' in Nairobi, Kenya, and Dar es Salaam, Tanzania. Those nearly simultaneous Aug. 7 bombings killed a total of 257 people, including 12 Americans.

Clinton did not elaborate on the threat.

The State Department evacuated all nonessential personnel from the U.S. Embassy in Tirana last Friday, citing a possible terrorist attack. One day before the Africa bombings, an Arabic language newspaper in London, al-Hayat, published a letter from the ``International Islamic Front for Jihad'' vowing revenge against the United States for the arrests of several of its members in Albania.

In his letter to House Speaker Newt Gingrich, R-Ga., and Senate Majority Leader Trent Lott, R-Miss., Clinton said a combat-equipped unit of 200 Marines from the 22nd Marine Expeditionary Unit and 10 Navy SEALS were deployed to Albania to provide extra security for those performing U.S. Embassy functions at Rilindja Ridge.

Clinton said U.S. military forces will continue to augment security at Rilindja Ridge ``until it is determined that the additional security support is unnecessary.''