Vice President Mondale has insisted on meeting with leading opponents of the martial law government of President Ferdinand Marcos in a move likely to further strain relations between the United States and the Philippines.

The six oppositions figures, who have been selected by the U.S. Embassy, intend to press Mondale at their meeting this afternoon to ask Marcos to release those opposition politicans jailed after last month's National Assembly elections.

The group will also call for continued American emphasis on human rights in its former colony, one of them said, even though Marcos' has reacted angrily to the U.S. campaign on the issue.

The U.S. Embassy was so worried about Marcos' reaction to the meeting that it tried to keep its role secret and encouraged some opponents to say they had initiated the meeting.

Those invited include former president Diosdado Macapagal, former foreign minister Salvador Lopez, two former senators, a Roman Catholic bishop and an activist nun.

Mondale was welcomed here yesterday afternoon on the first leg of his five-nation tour by children and teenagers singing and dancing in yellow, pink and orange costumes. The young people lining the route of his motorcade from the airport to the presidential palace were enthusiastic but far fewer in number than the throng that welcomed Chinese communist party Vice Chairman Li Hsien-nien in March.

In a brief airport statement the vice president said, "Where there are values and traditions which both our peoples cherish - freedom, individual liberty, human justice, democracy and national independence - I hope my visit can contribute to their greater fulfillment."

Senior officials on his plane have said he will bring up the human rights issue here, but that the trip's principal purpose is to convince leaders here and at his other stops - Thailand, Indonesia, Australia and New Zealand - of Washington's continued commitment to the security and economic health of this side of the Pacific Ocean.

This means some discussion between Mondale and Marcos of the slow-moving negotiations over a new treaty for continued U.S. use of the huge Clark Air Base and Subic Naval Base.

Marcos' interest in winning U.S. congressional approval for a new bases treaty, with substantially increased compensation, has been cited as one reason for one reason for his decision to call last month's election. The balloting ended with opposition charges of vote fruad and the arrest of some key anti-Marcos leaders who joined a peaceful protest march. Marcos' allies captured nearly every seat in the new 200-member interim National Assembly.

The government holds far fewer political prisoners today than it did in the first months after martial law was declared in 1972. Still, at least 500 and perhaps as many as 2,000 dissidents remain in jail. These include four candidates of the anti-Marcos assembly slate, former senator Francisco Rodrigo, attorney Teofisto Guingona, law professor Aguilino Pimentel Jr. and businessman Ernesto Rondon, who each polled about 1 million out of 3 million votes cast in greater Manila.

After U.S. Embassy officials made a private appeal last year, Marcos agreed to release slum organizer Trinidad Herrera, who had been arrested and allegedly tortured. Yet, he has angrily turned down American appeals to release former senator Benigno Aquino, in prison five years, so that Aquino might accept a university post in the United Sales.

One of the opposition leaders scheduled to see Mondale today called the Aquino case "a bit touchy" and said they would probably not bring it up. Instead, he said, they would ask for Mondale's help in the release of the other anti-Marcos candidates, the easing of controls on the local press and a return to genuine free elections.

One of the opposition leaders, who agreed to outline their strategy for the Mondale interview on the condition that his name not be used, said he planned to tell the vice president that he hoped "as leader of a friendly nation that brought democracy to the Filipinos you will do what is reasonable and necessary to help us to resume our democratic way of life."

The group includes none of the 21 persons who were candidates in the anti-Marcos Laban (Fight) assembly slate in Manila. To include them might have seemed to much a slap in Marcos' face, said one of those invited. Five of the 21 are now in jail and two others are sought by police.

Spokesman for Mondale declined to identify those dissidents invited, saying some were reluctant to have their names released. Some opponents of Marcos fear their supporters, many of whom describe Marcos as a puppet of American imperialism, might be unhappy at their meeting with a U.S. vice president.

Marcos has sought to use nationalist sentiments to his advantage, making occasional anti-AMerican speeches designed to increase his popularity with nationalists, curry favor with non-aligned nations and make Washington more anxious to sign a new bases treaty.

Yesterday, shortly before Mondale arrived, Marcos told a ceremony marking Philippine Air Force Day that "the special set of country have compelled us to assume a policy of self-reliance in matters of national security."

Marcos had many army recruits in civilian clothes out to welcome Mondale, but a similar group of recruits were also dispatched during the assembly election campaign a month ago to demonstrate in front of the American Embassy against "foreign interference."