The White House said yesterday it was prepared to give "most serious consideration" to Soviet leader Mikhail Gorbachev's call for additional international efforts on nuclear power plant safety and prompt reporting of accidents.

The U.S. statement also declared that the administration was ready to begin "a dialogue" between U.S. and Soviet experts on nuclear weapons testing. But it ignored Gorbachev's announcement that the unilateral Soviet ban on all underground nuclear tests would be extended until at least Aug. 6.

White House spokesman Larry Speakes turned aside Gorbachev's idea of a special summit meeting with President Reagan on the testing issue in a statement released five hours after the Soviet leader's speech.

Speakes said an invitation to the Soviet leader to come to the United States remained unanswered and "a meeting between the two leaders is possible this year if Mr. Gorbachev desires." The idea of a special session between the two on testing, Speakes said, was "difficult to understand . . . when the Soviet Union has up to now been unwilling to authorize a discussion at the expert level."

Speakes described Gorbachev as "misinformed" in his criticism of the arms control stand taken at the recently concluded Tokyo summit of Western leaders and called on Moscow to reply to current U.S. proposals.

The Soviet delegation at the Geneva arms talks yesterday asked for a special session with U.S. negotiators today, according to an administration official. In the past, the Soviets have used such meetings to present new proposals.

The administration is prepared for another of "Gorbachev's bold new arms initiatives," one administration official said. It was expected to be the Soviet leader's effort to regain the public initiative in arms control to counter the bad impact in Western Europe of Soviet withholding of Chernobyl information, he said.

With regard to Chernobyl, Speakes said the United States was "comforted" that Gorbachev said "the worst is behind us." But Speakes said "we are distressed" about Gorbachev's "unfounded charges" that the United States government encouraged inaccurate news reports. The stories that the Soviet leader criticized, Speakes said, were the "inevitable result of the extreme secrecy with which the Soviet authorities dealt with the accident in the days immediately following it."

"Unfounded accusations against others," Speakes said, "must not be used in an attempt to exonerate national officials from their obligation to inform the public promptly of accidents which may affect their health."

Reagan and Gorbachev have been jockeying over the nuclear testing issue for more than a year. The Soviet leader wants a halt to underground weapons tests while Reagan wants to continue tests but have better verification of a 1974 threshold test ban treaty that limits the size of such tests.

Yesterday's exchanges could be interpreted as a reiteration of these differences or they could signal an opening to long-awaited discussions on the issue. Gorbachev did not, as he has in the past, call on Washington to immediately join in the test moratorium, while the Speakes statement left out the past U.S. suggestion that the talks focus on on-site monitoring of tests.

The debate began openly last July when Gorbachev announced he was halting Soviet nuclear tests beginning Aug. 6, the anniversary of the U.S. use of the first nuclear bomb on Hiroshima. That moratorium was to last through 1985, but the Soviet leader extended it twice. Yesterday's statement would mean the Soviets will not test for a year.

Reagan ignored Soviet entreaties to join in the moratorium or seek a test ban and went ahead with the U.S. test schedule. After the ninth U.S. test since the announcement of the moratorium -- the second test in 1986 -- Gorbachev announced that the Soviets would resume their test program.