Security officials yesterday reported uncovering plots to kill President Arroyo and bomb foreign embassies, just as opposition leaders were calling for more protests urging the unpopular Philippines leader to resign.

Brigadier General Romeo Prestoza, head of the Presidential Security Group, said the Al Qaeda-linked Abu Sayyaf group and its allies were behind the planned attacks.

Few details were announced. That sparked opposition claims the government was using scare tactics in hopes of curtailing an anti-Arroyo demonstration Friday in Manila’s financial district and a Sunday prayer rally involving the Roman Catholic Church and a democracy icon, a former president, Corazon Aquino.

Ms. Arroyo, a staunch American ally plagued by long-running Islamic and communist insurgencies, has lurched from crisis to crisis since taking over in the country’s second “people power” revolt in 2001, fending off three impeachment bids and four coup plots. She has two years left in her term.

Her latest challenge intensified last week when former government consultant Rodolfo Lozada Jr. linked an ex-elections chief and Ms. Arroyo’s husband to an allegedly overpriced $330 million government Internet broadband contract — a contract the president canceled. Both men have denied the allegations, and Ms. Arroyo has not spoken directly about her husband’s alleged involvement.

Officials already had announced that security forces were going on high alert over concerns that communist rebels planned to infiltrate Friday’s protest by leftist groups and a prestigious group of business executives, the Makati Business Club.

A military spokesman, Captain Carlo Ferrer, said intelligence reports indicated the rebels planned “to create confusion and chaos.” The rebels vowed Wednesday to intensify attacks to weaken the government, but they have largely refrained from assaults that could hurt civilians.

The military chief of staff, General Hermogenes Esperon, said the assassination plot reportedly involved a sniper ready to attack Ms. Arroyo when an opportunity arose.

Ms. Arroyo’s planned visit to her country’s premier military academy this weekend in the northern city of Baguio was canceled and her remaining schedule was “under assessment,” General Prestoza, the Presidential Security Group head, said.

General Prestoza said police uncovered the assassination plot last week. “It’s not only the president who is the target, but also other people … and embassies,” he said, without offering any details.