Opposition legislators filed an impeachment resolution against President Ferdinand Marcos today, accusing him of "permitting and abetting economic sabotage" through massive overseas investments by relatives, friends and government officials.

The resolution, the first such impeachment measure initiated against Marcos in his 20 years in power, was filed by 35 opposition members of the National Assembly shortly before the president gave a state-of-the-nation speech opening the second regular session of the 200-seat legislature.

The impeachment move followed press reports in the United States that prominent Filipinos had channeled tens of millions of dollars into U.S. investments through shadowy holding companies as part of a massive and damaging capital outflow estimated to total billions of dollars since the 1960s.

Among those cited as maintaining large American investments were Marcos' wife Imelda, two Cabinet ministers and several friends of the president.

Backers of the impeachment resolution conceded that the measure had practically no chance of passage in the assembly dominated by members of Marcos' ruling party. But they said it would draw attention to the "economic treason" that they claim the investment scandal represents.

Marcos, in his 40-minute speech, appealed for unity to "save the republic" but made scant reference to the two main issues preoccupying the legislators: the investments scandal and a move by Marcos' own party to abrogate a military bases agreement with the United States.

Marcos noted near the end of his speech that he had ordered his justice minister to investigate allegations of "hidden wealth" held by Filipino officials and private individuals "irrespective of party" and said the Foreign Ministry was seeking documentary evidence from foreign sources.

Marcos said he had also asked the justice minister to investigate charges now before a U.S. federal grand jury in Alexandria, Va., that $6 million was diverted from a $35 million Pentagon-financed contract to provide communications equipment to the Philippines under a U.S. Foreign Military Sales program.

Regarding a dispute over compensation for U.S. use of two large military bases here, Marcos indicated that he would handle the matter personally as the country's "foreign policy formulator," but he said he would welcome advice from the assembly.

Defense Minister Juan Ponce Enrile filed a legislative resolution Friday calling for the abrogation and renegotiation of the military bases agreement because of a recent U.S. House of Representatives vote to cut military aid to the Philippines next year.

The House disapproved a Reagan administration request to give the Philippines $100 million in military aid and $95 million in economic assistance in 1986 as part of a five-year agreement to provide $900 million for use of Clark Air Base and Subic Bay Naval Base. Instead, the House voted for $155 million in economic aid and only $25 million in military aid, a package that still met the $180 million a year called for in the current 1984-89 agreement.

The agreement, signed in 1979 and subject to review every five years, expires in 1991, at which time either side may abrogate it with one year's notice.

In his call for renegotiation of the agreement, Enrile complained that the aid compensation package really amounted to "rent" and that "tinkering" with the military and economic allocations already agreed amounted to U.S. intervention in Philippine affairs.

While the Marcos government shared Enrile's "indignation" over the House vote, members of the ruling New Society Movement said that the resolution was likely to be buried in a committee in favor of a milder resolution to be filed Tuesday.

Labor Minister Blas Ople said the new resolution would create a special legislative commission to study Philippine-U.S. issues generally. Enrile's resolution, he said, "will be properly received in a receptacle," where it will "get a soft landing."

Opposition legislators today dismissed the outcry over the bases issue as little more than a "smoke screen" to divert attention from the overseas investments scandal.

In the impeachment resolution filed by Antonio Cuenco and 34 other legislators, Marcos was accused of having "callously and arrogantly disregarded" his own presidential decrees and pronouncements against draining the country of foreign exchange.

Marcos "not only has failed to prevent the systematic looting of the country's finances but, on the contrary, has permitted and even abetted it," the resolution said. It called his "belated order" for a probe by his justice minister "meaningless, and even offensive, under a regime where he can legalize and immunize anything by the misuse of his vast and vague powers."

The document also charged that from 1980 to 1984, Marcos improperly disbursed 1.26 billion pesos ($70 million at the current exchange rate) "out of the government share of casino earnings to finance various projects."

In his speech, Marcos painted an optimistic picture of efforts to cope with a growing Communist insurgency.

Communist rebels, he said, "are beginning to surrender in droves" because of a more effective military counterinsurgency campaign.