Philippine activists picketed the US embassy on Saturday and burned a cardboard American flag and mock stealth bomber, vowing to launch a campaign opposing a plan to allow more US troops in the country.

About 50 members of the leftist New Nationalist Alliance (Bayan) also held a huge effigy of Uncle Sam with another of Philippine President Benigno Aquino labelled as his "dog", as riot police prevented them approaching the mission.

"If we allow more US troops to enter our country, the entire archipelago will be transformed into one military outpost for US hegemonic interests," Bayan said in a statement distributed at the rally.

Philippine officials have welcomed plans for a greater presence from the military of its former colonial ruler, seeing it as a counterbalance to recent Chinese aggressiveness in the South China Sea.

China and the Philippines have territorial disputes over the South China Sea and Manila has accused Beijing of using intimidation to press its claims.

The Philippines previously hosted huge US military bases until the Philippine Senate, stirred by nationalist opposition of groups like Bayan, voted to close them down in 1992.

US and Philippine officials say they are not interested in new US bases but merely in more joint exercises and more US troops rotating through the country.

While Filipinos are largely pro-American, small but vocal groups in the media and influential Roman Catholic church are fervently opposed to a US presence.

International affairs specialist Rene de Castro said the Philippine government would have to carefully explain its decision to overcome such anti-American sentiment.