A wealthy Philippine athletic figure has mysteriously disappeared following reports that he and Imee Marcos, 26, elder daughter of Philippine President Ferdinand Marcos, were secretly married in the United States last month against her family's wishes.

Tommy Manotoc, 33, one of the Philippines' top amateur golfers and a professional basketball coach, reportedly was last seen Tuesday night dining with Imee Marcos in an elegant restaurant in Makati, a suburb of Manila.

Informed sources in the United States told The Washington Post that Manotoc's relatives suspected that the Marcos family may have had a role in Tommy's disappearance because of their opposition to the purported marriage.

Carmen Manotoc, Tommy's mother, was quoted in a United Press International dispatch from Manila Friday as saying, "Considering that they were opposed to the marriage, it couldn't be anybody else but them." She added, "many conjectures" surround the case.

Presidential spokesman Adrian Cristobal denied that the couple had married, that Marcos and his wife opposed the relationship or that they had a hand in Manotoc's disappearance. "Why should the president be responsible for any mishap just because of the apparent relationship between Imee and Tommy?" Cristobal said, according to UPI.

The presidential palace issued a statement saying that its assessment was that Tommy Manotoc was "in the hands of . . . kidnapers who are either subversive or criminal elements who have sent a ransom note to the family."

The Manotoc family, however, immediately denied a ransom demand had been received.

Imee Marcos could not be reached for comment.

The chief of the Philippine constabulary, Lt. Gen. Fidel Ramos, declared at a press conference, "There is no clear and hard evidence that any crime has been committed."

Tommy Manotoc's lawyer, Roberto San Jose, told newsmen today that he had handed over the couple's marriage certificate, which he said he thought was issued in Arlington, Va., to a security officer of Imee Marcos' Wednesday. Two weeks ago, Imee Marcos requested the certificate, which had been entrusted to the lawyer by Tommy Manotoc, San Jose said.

Because of the New Year's holiday the records of the clerk of court in Arlington could not be checked Friday.

The lawyer added that he only remembered the date of the marriage as in the first week of December.

Imee reportedly is particularly close to her father and accompanied him as an aide to the conference on international economics held in Cancun, Mexico in October. She studied political science at Princeton University and is a television and stage actress.

The Marcoses were apparently only informed of the marriage after the ceremony, according to Tommy's younger brother, Ricardo Jr.

Tommy Manotoc had been separated from his first wife, Aurora Pijuan, chosen Miss International 1969. They have two children aged 10 and 14. Pijuan said she was aware of her husband's relationship with Imee and had agreed to his suggestion of a divorce.

Tommy Manotoc left the Philippines in November to try to get a divorce in Switzerland and to petition the Vatican for an annulment of his first marriage, according to Manotoc family sources. He obtained a divorce in the Dominican Republic and returned to the Philippines Dec. 16 at the request of President Marcos, the sources said.

In the predominantly Catholic Philippines divorce is not legal.

Carmen Manotoc said Tommy told her that he and Imee had informed Mrs. Marcos of their marriage when the first lady was in New York. Mrs. Marcos reacted angrily, Mrs. Manotoc quoted Tommy as telling her.

The Manotoc family is related to several of Marcos' political foes, including Raul Magalapus, who heads an anti-Marcos front, the Movement for Free Philippines in Washington, and former newspaper publisher Eugenio Lopez, also in exile in the United States.

President Marcos has telephoned Tommy's father, Ricardo Manotoc Sr., and assured him that "the armed forces are looking into it," Ricardo Jr. said. "I feel that . . . making it public is the only way to protect my brother," Ricardo added.

The presidential palace had asked the foreign press not to pursue the story. "The government promises to reveal all the details of this matter very soon hoping as it does that minimizing the statements will help save the life of Tomas Manotoc."

The Marcoses have two other children, Ferdinand Jr. 24, and Irene, 21, who are both single.