In the most explicit policy statement yet on the subject, top U.S. officials yesterday warned Philippine President Ferdinand Marcos that his government needs to do much more to deal with the country's growing economic, political and military problems.

"The Philippines cannot afford a business-as-usual approach to the communist insurgency or the urgent need to deal with its root problems," the State Department's senior Asian expert said yesterday.

Referring later to the recent dismissal of Philippine Foreign Minister Arturo Tolentino and the resignation -- not yet accepted -- of Labor Minister Blas Ople, both of whom are known as independent men, Assistant Secretary of State Paul D. Wolfowitz said: "Forcing moderates out of government are not steps in the right direction."

Without economic, military and political reforms, and if the communist insurgency continues unchecked, the rebels could reach a "strategic stalemate within three to four years" in that they "will have attained enough military muscle to prevent their defeat on the battlefield," said Richard L. Armitage, assistant secretary of defense for international security affairs.

Both officials testified before the House Foreign Affairs Asia subcommittee on the Reagan administration's recent $275 million aid request for the Philippines, which includes $15 million more in military assistance than the administration had asked for last year.

Later, describing the strength of the New People's Army, the armed wing of the Communist Party of the Philippines, Armitage said, "Right now, the insurgents pick the time and place of the party and the government responds."

In testimony yesterday, Armitage said that the armed strength of the insurgents, estimated between 10,000 to 12,000, could be as high as 15,000, the highest figure given to date by the United States. He also said that 33 percent of the Philippines' 42,000 villages, or barangays, are believed to be "affected in some measure" by the communists, compared to the figure of 20 percent cited previously.

Although both officials pointed to progress made in the past year, Wolfowitz noted with concern the recent failure of witnesses to appear in the trial of Gen. Fabian Ver, the Philippine armed forces chief of staff. Ver, along with seven other military men, has been charged with conspiracy to cover up the murder of opposition leader Benigno Aquino Jr.

"It is important that the Philippine government take all measures possible to ensure the appearance of witnesses and their ability to testify freely," Wolfowitz said.

The future course of U.S.-Philippine relations depends on the credibility of the trial, as does the relationship between the Philippine government and its people, he said.

If the trial is carried out "in a way that Filipinos judge to be fair and impartial," Wolfowitz said, it has the potential "to cleanse the entire military institution of the stain of the Aquino murder."

In recent weeks, Marcos has announced that he would reinstate Ver if the general is acquitted, a move that Philippine opposition leaders and lawyers have said could prejudice the prosecution's case.