Moves to unify the Philippine opposition to President Ferdinand Marcos for a scheduled presidential election in February fell apart this morning amid a last-minute dispute on the announcement of a single opposition ticket.

Former senator Salvador Laurel said at a news conference packed with his supporters that he was still a candidate for president against Marcos in the early election set for Feb. 7. He said he had rejected an offer to run for vice president under Corazon Aquino because she refused to join his political party.

But Aquino later denied Laurel's version of the dispute.

Supporters of both Laurel and Aquino held out the possibility that unity might still be achieved after further negotiations.

Laurel heads the United Nationalist Democratic Organization, known as Unido, which he described as "the largest and most organized opposition political party in the country today."

Aquino, 52, the widow of assassinated opposition leader Benigno Aquino, was drafted last week as the presidential candidate of a newly formed coalition after supporters gathered 1.2 million signatures on a petition urging her to run.

Laurel, 57, said that he had accepted Aquino's offer to run as her vice presidential running mate and that on Thursday Aquino had accepted his demand that she join his party. But, Laurel said, Aquino changed her mind this morning "for reasons undisclosed. This sudden and unexpected refusal on her part to run as the Unido candidate leaves me no choice now but to decline her offer to run as her vice president," Laurel said as supporters cheered and applauded loudly. "I can sacrifice myself, I can sacrifice the presidency, but I cannot sacrifice my party and my principles."

Laurel added that he would file his candidacy for president formally on Monday.

A spokeswoman for Aquino said Aquino had agreed to run under a combined party to be called Unido-Laban ng Bayan. But she said it was Laurel for whom the merger of Unido with Aquino's Laban ng Bayan party (people's struggle) was unacceptable.

Laurel told reporters after the press conference, "The door is open any time" to Aquino but only if she now agrees to run as vice president under Laurel.

Political analysts have said that an Aquino-Laurel ticket would be a formidable challenge to Marcos, but that a divided opposition had little chance of defeating the president in the February elections.

The two opposition sides have until Dec. 11, the deadline for registration of candidates, to reach an agreement.

Laurel and Aquino had been expected to announce a joint presidential ticket today in which the highly popular Aquino would run as president and Laurel would set aside his long-held ambitions by accepting the vice presidential candidacy.

Another aspirant, Eva Kalaw, announced yesterday that she was withdrawing from the race for the sake of unity.

But there had been signs yesterday of increasing discord in the ranks of the opposition.

Laurel issued a statement last night condemning what he said was a "campaign of disinformation against me" aimed at promoting Aquino for president.

He cited a statement by Benigno Aquino's brother, Agapito Aquino, who said that there was "an 80 to 90 percent chance" of an Aquino-Laurel ticket against Marcos and his still unknown running mate.

Sources in the ruling New Society Party said Marcos' choices have been narrowed to four possibilities: businessman Eduardo Cojuangco, a first cousin of Corazon Aquino; Prime Minister Cesar Virata, Assemblyman Arturo Tolentino and Labor Minister Blas Ople.

Marcos and his wife, Imelda Marcos, have said that she will not run.

Aquino has been estranged from Cojuangco for the past 20 years as a result of political rivalry in their home province of Tarlac, central Luzon. Cojuangco is a close Marcos ally who controls the coconut monopoly.