Human rights violations have increased under President Corazon Aquino's administration and the United States shares responsibility, a leftist social action group charged today. Meanwhile, suspected Communist rebels ambushed and killed a police informant early today in Manila's Tondo district, a stronghold of urban guerrillas. Petrolino Lim suffered three gunshot wounds and died a few hours later in a hospital, police said. The Philippine Alliance of Human Rights Advocates said it would file a petition with the U.N. Commission on Human Rights in New York asking it to condemn the U.S. and Aquino governments for ``gross and systematic violations of human rights of the Filipino people.'' Alvaro Senturias, an alliance official, told a news conference that the petition would show that ``human rights violations have increased under the Aquino government.'' The alliance distributed copies of the petition, which cited numerous specific allegations of abuses, including murder, the bombing of civilians and forced evacuation of villagers. Most of the incidents stemmed from the government's effort to step up the war against Communist rebels' 19-year-old insurgency _ employing armed vigilantes, for example, the group said. There was no immediate comment from the government, which came to power nearly two years ago on the promise of restoring human rights after 20 years of authoritarian rule under ousted President Ferdinand Marcos. The alliance, an umbrella group for several leading church-affiliated human rights groups, says in the petition that the United States ``has intensified its intervention in the counter-insurgency program.'' ``The Aquino government has become more subservient to the dictation of the U.S. policy makers and counter-insurgency experts,'' it says. The alliance said that despite its stated commitment to human rights, the Aquino government had made little effort to punish those in the military who had committed abuses under the Marcos administration. The military has said that many of the church-affiliated groups that comprise the alliance are communist-infiltrated. It says they unfairly blame soldiers for abuses without criticizing similar actions by the rebel New People's Army. Mrs. Aquino was swept to power in a February 1986 military-civilian uprising that toppled Marcos, who lives in exile in Hawaii.