Syria's president criticized a proposed U.S.-Iraqi security pact for the first time Sunday that would keep American troops in Iraq for three more years.

Bashar Assad said U.S. troops contribute to regional instability and should withdraw from Iraq as soon as possible. He pointed to a recent American raid inside Syria near its border with Iraq as evidence that the U.S. will use Iraq as a base to attack its neighbors.

"The latest American aggression on Syrian territory shows that the presence of American occupation forces constitutes a source of continuous threat to the security of Iraq's neighboring states and a factor of instability for the region," he told group of Arab parliamentarians meeting in Damascus.

U.S. officials have said last month's raid targeted a top Al Qaeda in Iraq figure. Syria has asked for proof and said eight civilians were killed in the attack.

Iraq has asked the U.S. for an explicit ban in the proposed security pact on the use of Iraqi soil for attacks against the country's neighbors. The U.S. has replied to the request, but the details are not known.

Assad lashed out at the pact Sunday and called on other Arab countries to reject it.

"The Arab position has to be clear and unified, that is to stress the necessity of ending the occupation and confronting any attempt to impose any agreement that infringes on the sovereignty of Iraq and its security and harms overall Arab national security," said Assad.

Iran, a key ally of Syria, has also criticized the pact, which would keep U.S. troops in Iraq until the end of 2011.

The Iraqi parliament must approve the agreement by year's end when a U.N. mandate expires. Failure to approve the agreement or get the U.N. Security Council to issue a new mandate would force the U.S. to suspend operations in the country.

The Bush administration has clashed repeatedly with Syria since the U.S.-led invasion of Iraq in 2003. Syria opposed the war, and Washington has accused Damascus of not doing enough to stop militants from crossing its border into Iraq.