South Korea's new opposition leader accused President Park Chung Hee's government today of using police power to restrict the press, suppress human rights and squelch dissent.

The speech to foreign corresponts in Seoul by Kim Young Sam, recently elected chairman of the New Democratic Party, was one of the toughest antigovernment statements in years outside the National Assembly and appeared to be an intentional test of a decree banning political dissent.

Hundreds of South Koreans have been jailed for less direct criticisms.

Kim said he hopes to express his views to President Carter during his visit to Seoul later this month. Calling the results of the recent National Assembly election - in which his party won a plurality - a sign of lack of confidence in the government, Kim declared:

"The Park regime should peacefully surrender the reins of power in face of this vote of no confidence."

Kim said he has made a formal request through diplomatic channels to meet with Carter so "he can hear what the people wish to stay to him."

So far as is known, the White House has not responded to such requests but has let it be known through the State Department that Carter will discuss human rights in South Korea with President Park.

Carter's schedule for the Korean visit, released candidate Kim Dae Jung, have argued Carter not to make the visit because they assert it would strengthen Park's government by appearing to support his policy of dealing with dissent.

Kim Young Sam, said he welcomed Carter's visit "in principle," but added, "Our people will be severely disappointed if [it] results merely in strengthening of a particular political regime."

Kim Young Sam was elected party chairman May 30 by a slender majority after a strong endorsement from Kim Dae Jung, who as the party's presidential candidate running against Park in 1971 received 45 percent of the vote.

The Kim's faction had accused the party's previous leadership of cooperating with Park's ruling party and of failing to oppose the president forecefully on such issues as dissent and rights.

In elections for the National Assembly last December, the opposition party outpolled Park's party, by about 1 percent of the total vote. Park controls the legislature because he is allowed to appoint one-third of its members.

"If democratic principles had been observed, the New Democratic Party would have become the ruling party," Kim Young Sam said today. He had asserted last month that while he was campaigning for the party leadership, government agents raided his campaign offices, seized pamphlets, and kept him under surveillance.

Accusing the government today of using police power to divide the political opposition, restrict the press, and suppress human rights, Kim said, "Our party will take the lead in fighting against these things."

Its first demand, he said, would be to rescind the presidential proclamation that bans any criticism of the government outside the halls of the National Assembly.

He also accused the government of damaging the prestige of South Korea by its treatment of Kim Dae Jung, who was jailed for nearly three years for criticizing Park, and for permitting such major scandal as the case of Tongsun Park, who has accused of paying money to influence U.S. congressmen.

Kim Dae Jung reportedly was picked up by police for questioning last night and released after three hours.

Kim Young Sam also insisted that opposition leaders should be permitted a role in unification negotiations with North Korea and said he is willing to meet with North Korean President Kim II Sung.