MANILA, Philippines (AP) _ About 200 protesters scuffled with riot police outside the U.S. Embassy in Manila today, demonstrating against a pact that would allow large-scale U.S. military exercises in the country.

The activists, belonging to the National Democratic Movement, ran past riot police and destroyed a plastic cover protecting the U.S. government seal at the embassy's entrance. Police pushed them back with shields and truncheons, injuring at least one protester.

Philippine police have been placed on alert nationwide ahead of a vote next week by the Philippine Senate to decide whether to approve the Visiting Forces Agreement. The draft agreement was signed last year by Philippine and U.S. officials to regulate U.S. war exercises and ship visits.

Protests against the VFA by leftist groups have been held almost daily in recent weeks at the Philippine Senate and the U.S. Embassy. Clashes have occurred between protesters and police, but with no serious injuries.

Police spokesman Nicanor Bartolome said police are under orders to be tolerant of protesters.

The activists today burned a tire and U.S. flags, and blew up effigies of three pro-agreement Philippine senators using firecrackers.

Riot police also used truncheons to force back a group of protesters at the seaside Senate building.

Senate majority floor leader Franklin Drilon said a preliminary vote on the agreement could be held later today or Tuesday. A final vote is expected next Monday.

The VFA must have the support of at least 16 of the 23 senators for it to pass. Senator Rodolfo Biazon, a former military chief of staff, said at least 18 senators currently favor the pact.

Supporters say the VFA will help protect regional peace and stability and strengthen the Philippines' armed forces, which are among Asia's weakest.

Critics say the pact would limit the Philippine government's right to prosecute American soldiers who commit crimes in the country, promote prostitution, and drag the Philippines into conflicts with the United States' enemies.

Under the accord, the United States would generally have legal jurisdiction over U.S. soldiers who commit crimes while on duty, and the Philippines would have jurisdiction over those who commit crimes while off duty.

The United States halted major exercises in the Philippines and visits by U.S. military ships in December 1996, when Manila ended a legal loophole that shielded U.S. military personnel from prosecution.

Military ties with the United States, which ruled the Philippines for nearly half a century, have remained sensitive since the Philippine Senate forced the closure of the last U.S. base in 1992.