MANILA, SEPT. 16 -- Vice President Salvador Laurel, citing "basic, fundamental differences" with President Corazon Aquino over her handling of the communist insurgency, left his Cabinet post as foreign secretary today, breaking all political ties with Aquino.

It was unclear, however, whether Laurel quit or was fired. Laurel's strong statements today forced Aquino to make an unscheduled appearance on national television to accept the resignation and announce the first phase of a Cabinet shake-up in the aftermath of last month's aborted military coup.

Laurel, who formed a reluctant coalition with Aquino in 1985 to oust president Ferdinand Marcos, will retain his elected post as vice president.

Aquino, in her television address, also appointed two former military men to top posts and accepted "with deep regret" the resignation of Jaime Ongpin, her Harvard-trained finance secretary. Ongpin has come under sharp criticism here for negotiating a debt rescheduling package with foreign creditors that Aquino has said falls "short of our expectations."

She named Vicente Jaime, the public works secretary, to replace Ongpin. Jaime is respected within the business community.

The entire Cabinet offered to resign last week in order to give Aquino more flexibility in reshaping and restoring confidence in her administration following the Aug. 28 coup attempt.

Laurel today said his resignation was "irrevocable." But sources said Aquino had planned to drop the outspoken vice president from the Cabinet because of lingering strain and mistrust between them and that Laurel called today's news conference to preempt her. His session with the press followed a two-hour meeting with Aquino, attended by members of both families.

Aquino named Foreign Affairs Undersecretary Manuel Yan, a retired general, to replace Laurel. Selection of the respected former armed forces chief was seen as an attempt to head off anger in the military over Laurel's departure. Laurel, an old-style machine politician, is viewed as being more conservative than Aquino and more closely allied with the military than the leftist lawyers who advise her.

Another retired general, Salvador Mison, was named to replace the customs commissioner, Alexander Padilla. The customs bureau is widely regarded as the most corrupt department in the government. Curbing corruption was among the demands of the leaders of the attempted coup and of Aquino's military critics.

Aquino's detractors in the military, including the rebel soldiers, also have sought the removal of leftists and communist sympathizers in her government. The person most often attacked is Executive Secretary Joker Arroyo, who defended well-known communists when he was a human rights lawyer during Marcos' martial law regime.

Aquino did not mention Arroyo in her broadcast. Some observers said Arroyo apparently had begun a last-ditch effort to convince Aquino to keep him and fire his critics, specifically Laurel and finance secretary Ongpin. More changes are expected to be announced this week.

In his news conference, Laurel accused the president of reneging on a bargain struck before last year's election. According to Laurel, he agreed to run as the vice presidential candidate on an Aquino-led ticket in exchange for free rein to run the government and the authority to name 30 percent of the Cabinet.

Since the election, Laurel said he has been treated as "an outsider looking in," whose views are ignored on most major policy decisions. He said he has felt "frustrated."

Laurel said he will use the vice-presidency as a platform to criticize the government "with greater freedom."

He was critical of Aquino's handling of the communist insurgency over the past 18 months and of an apparent breakdown in peace and order in the country.

"I can't understand why we have certain people in the government who are sympathetic to the communists or who are perceived to be sympathetic to the communists," Laurel said.

Asked to identify the communist sympathizers, Laurel said he had promised military intelligence not to divulge names.

After Laurel's remarks, Aquino went on national television to announce the first round of Cabinet changes. She rebutted Laurel's accusations, saying she had dropped her earlier, failed policy of reconciliation with the communists after the collapse of a cease-fire and peace talks in February. She noted that she had devoted a third of her July state-of-the-nation message to the financial and equipment needs of the armed forces.

"This is my policy: it is a combination of, one, military offensive, two, respect for democratic practices and, three, support for economic programs that will uplift our people," Aquino said.

"It is as clear as I can make it. The vice president has said he does not agree with this policy. I have sadly accepted his resignation."

Under the Philippines' new U.S.-style constitution, all new presidential appointments must be confirmed by a joint bipartisan congressional committee on appointments.

Several senators, who favor setting a ceiling on the amount of export earnings that can be used to pay foreign loans, have said they will use finance secretary-designate Jaime's confirmation hearings to resume the debate over repudiation of part of the country's massive $28 billion foreign debt.

Yan apparently was given the foreign affairs post after Emmanuel Palaez, the Philippine ambassador to Washington, said he was not interested, sources said.

No change is expected in Philippine foreign policy or in its relations within the main noncommunist organization in the region, the Association of Southeast Asian Nations, or ASEAN.