A Philippine Cabinet minister said today that inertia has hindered President Ferdinand Marcos' ability to implement needed reforms and that a new generation of leaders is the only guarantee for the country's stability.

Labor Minister Blas Ople, one of the more outspoken members of the Marcos Cabinet, said political, economic and military reforms are needed for the country to survive. Referring to Marcos' leadership, he said, "You know, when you have been in power for so long, a degree of complacency sets in. The old elan disappears."

Ople, who has been labor minister for 18 years, has a reputation for being independent and has objected to Marcos' use of decree powers and patronage. Marcos has scolded him publicly in recent months for comments he made about Marcos' health and political and economic conditions in the Philippines.

Ople, who is known to have presidential ambitions, has offered his resignation, but so far, it has not been accepted.

In an interview here, Ople also warned of a Philippine backlash if the United States went too far in applying pressure on Manila to make the needed reforms.

His comments were the first high-level reaction to the recent release in Washington of an official U.S. policy paper on the Philippines. The State Department paper, dated Nov. 2, calls for the use of diplomatic and economic tools to encourage a peaceful and democratic succession to Marcos' weakening rule. Although Marcos is part of the problem, the paper says, the United States considers it necessary to work with him to push for the reforms needed to fight a mounting Communist insurgency.

Should Marcos refuse to undertake or block reforms desired by the United States, or should he agree and fail to follow through, the paper recommends that the administration "discreetly publicize" its views to increase internal pressure on Marcos and send tangible "signals" of noncooperation by tactics such as delaying disbursement of U.S. funds and "negative votes in multilateral forums."

Earlier this week, in Washington, the House foreign affairs subcommittee on Asia and the Pacific drastically cut military aid to the Philippines for fiscal 1986 from the $100 million requested by the Reagan administration, which was divided equally between grants and loans, to $25 million in grants. The panel raised economic aid from $95 million to $155 million.

On Friday, Defense Minister Juan Ponce Enrile issued a statement saying U.S. congressional efforts to cut military aid to the Philippines amount to intervention in its internal affairs, Reuter reported.

Enrile also said changes in the economic and military aid allocations might violate the agreement under which the United States maintains military bases in the Philippines.

Ople said that the U.S. policy paper was "an exercise in exacerbation" and that the Philippines "is not as vulnerable as they [the Americans] make it to be."