Imelda Marcos said today, with some qualification, that she will abandon politics next year because she finds herself considered "suspect" in the assassination of opposition leader Benigno S. Aquino Jr.

She said she had found herself considered "suspect" and a "threat" to succeed her husband, President Ferdinand E. Marcos, and had reached the limit of her "human sensitivity."

"I am just dying to get out," she said at a news conference with foreign reporters.

Her declaration was received with skepticism by members of the political opposition, which is campaigning to force the president's resignation and bring about a new "government of reconciliation."

"She wants to get out of range," said Salvador Laurel, leader of the opposition. "Nobody believes" she will resign her government positions, he added. "People would rather judge her by what she does than what she says."

Mrs. Marcos is a powerful political figure.She holds three important government posts--minister of human settlements, governor of metropolitan Manila and member of the executive committee appointed by the president and charged with running the country in the event he is incapacitated.

It has been assumed for years that she would attempt to succeed her husband if he retires.

Her recent comments on quitting politics have been interpreted by many here as the government's attempt to defuse the dissent that has built steadily since Aquino was shot on Aug. 21 as he returned from the United States.

Many here suspect that his death was ordered by someone in the government, a charge that the Marcoses have emphatically denied. No one has been arrested and the suspension last week of a high-level investigation has added to demands that the president resign.

Friday, about 10,000 people in the business and financial district of suburban Makati paraded in an anti-Marcos protest, a signal that the business community is unhappy with the government.

The Roman Catholic Church also has stepped up its pressure by planning a series of national noontime prayers this week, accompanied by the tolling of church bells. In the prayer broadcast throughout the country on church radio today, Catholics were urged to pray that the almost defunct investigating commission would find the courage to "seek the truth" in the slaying.

The opposition is building up to what it expects will be a huge protest rally Wednesday not far from the presidential palace.

Many observers here believe the government must make some dramatic move to deflect the opposition. Mrs. Marcos' statement about abandoning politics is considered by them as a first move in that direction.

Reports circulate periodically that Ferdinand Marcos is seriously ill and might retire at any time, creating a vacancy he might try to fill with his wife.

One of her closest allies in the government is Gen. Fabian Ver, armed forces chief-of-staff. The suspicion is widely held that the military had something to do with Aquino's death.

Mrs. Marcos had said earlier she was considering quitting politics next year but her remarks today were more definite.

She said her decision not to seek reelection to the National Assembly next year is "definite and unequivocal" and asserted that would mean she could not remain as Manila's governor or a minister of the national government.

However, she said she had reached no decision about retaining membership on the executive committee. In theory, that committee could run the country only for a limited period, but it would have full presidential powers in the interim, including power to invoke martial law as Marcos did from 1972 to 1981.

Mrs. Marcos also at first hedged when asked if she would under any circumstances succeed her husband as president. She said, "I don't think so." Later, advised by an aide to be more precise, she said there was no chance she would succeed him.

She accused foreign news media of creating suspicions among the Filipinos. Asked what those suspicions are, she replied: "that I had something to do with the killing" of Aquino. She said she also was considered likely to succeed her husband and said some perceived that as a "threat."

"The best way is to just get out," she said. "I have reached the limit of my human sensitivity." She said she would retire to the private sector and attempt to build up the economies of rural areas.

Mrs. Marcos also blamed the opposition for the Aquino tragedy, asserting that it had "bullied" their former leader into leaving the United States and returning to Manila.