The Kremlin admitted last night that Soviet border guards crossed into Chinese territory this week, but said it was a mistake that occurred while the guards were "pursuing a dangerous and armed criminal" at night.

The official government news agency Tass sought to downplay the incident, implying that contrary to Peking's version, no Chinese were injured. "The Soviet servicemen did not undertake any actions involving Chinese citizens," Tass said.

Peking has accused the Soviets of an "organized military provocation" involving a helicopter, 18 boats and 30 servicemen who moved 2.4 miles across the sensitive border along the Ussuri River, beat up some Chinese, shot and wounded others and dragged 14 of them to the river bank and seemingly threatened abduction into Soviet territory.

Despite Tuesday's incident, senior Chinese and Soviet diplomats resumed border talks in Peking yesterday, suggesting both sides may be interested in continued efforts to ease border tensions. The talks are conducted by China's Vice Foreign Minister Yu Chan and his Soviet counterpart, Leonid Ilyichev.

The two-paragraph Tass statement gave a much different, milder version of the incident. Tass said that a group of Soviet border guards in pursuit of the unamed criminal, "having mistaken the Chinese bank for the Soviet Krestovsiye Islands (in the Ussuri) landed there and penetrated over a small distance into Chinese territory. The Soviet servicemen did not undertake any actions involving Chinese citizens, but finding out that they had inadvertently landed on Chinese territory, they immediately left."

Peking, which disclosed the incident Thursday, has been demanding an apology from the Kremlin. The Soviet ambassador to China delivered his government's regrets yesterday. Tass said: "Regrets over the incident have been expressed to the Chinese side."

According to Tass, the incursion occurred "on the night of May 8 to 9." But the Soviet account carried none of the seeming precision of Peking's version of the incident, one of the most serious outbreaks along the volatile border between the two Communist rivals since the 1969 Soviet-Chinese border clashes left dead on both sides.

The Tass statement did not say how many servicemen crossed the river or by what means, did not say what weapons the "dangerous and armed criminal" was carrying or who it was or what crime had allegedly been committed. The Kremlin version also did not disclose whether the quarry had been found and returned to Soviet turf or left among the Chinese.

In 1969, traditional border tensions between the two countries, which share more than 4,000 miles of border - the longest common boundary in the world - boiled into a series of deadly clashes across the Ussuri. The Soviets later claimed that "hundreds" of Chinese troops had been killed.

The Chinese and the Soviets have argued for years over who controls islands in the middle of the Amur and Ussuri Rivers, which serve as the border of China's northeastern most province, Heilungkiang. The reported site of Tuesday's raid, the Yueyapao District of Heilungkian's Huling County, is not known to have any disputed islands like Chentao (Damansky) Island, 40 miles to the north. There reported Chinese ambush of Soviet troops in March 1969 began months of clashes.

The latest Soviet incursion and subsequent expressed regret fit the confused, sweet and sour pattern of Chinese-Soviet relations in the last several months Moscow has made several efforts to seek improved relations with Peking since the 1976 death of Chinese Communist Party chairman Mao Tse-tung, a bitter Soviet foe.

But many of Moscow's approaches have been clumsy, such as their effort shortly after Mao's death to reopen party-to-party relations instead of first trying to mend the less sensitive government relations which the Chinese clearly preffered.

-TTS After the Chinese rejected a Soviet request in late February to sign a statement on improved relations, Soviet President Leonid Brezhnev went on a saber-rattling tour of Sino-Soviet border areas and then sent Ilyichev, the chief Soviet border negotiator back to Peking after a year's absence. The Chinese had rejected the earlier Soviet gesture because it included no promise of a mutual disengagement of troops on the border but they were willing to resume talks with Ilyichev.

Just yesterday, Peking, through its official New China News Agency again accused the Soviet Union of acting like "czarist Russia, Germany and U.S. imperialists" in the border incident.

It is impossible to check the veracity of either capital's account of the incident beyond the obvious facts that Peking asserted it occured and the Kremlin acknowledged it and apologized. But it is worth recounting that just a few weeks ago, in telling of the South Korean airliner that was downed on Soviet soil, the two Tass accounts never mentioned that Soviet jet fighters had shot the plane down or that two passengers had died and others were injured.