The Chinese government today welcomed North Korea's recent strengthening of ties with the Soviet Union.

The Foreign Ministry statement was in sharp contrast with the days when the Peking government might have held silent or even expressed alarm. But the statement reflects the recent shifts in relations in Asia among regional powers, the United States and the Soviet Union.

At a regular weekly press briefing, a Chinese foreign ministry spokesman said the Chinese "positively appraise" North Korea's "independent foreign policy and are pleased to see the development of its relations with the Soviet Union."

The North Koreans were long considered closer to the Chinese than the Soviets but have engaged in a pattern over the years of playing one side off the other. Several diplomats interviewed here said they saw no sign that this pattern would change.

But some diplomats here believe the Chinese are in reality concerned about the Soviets' recently strengthened ties with North Korea and are putting the best face possible on a delicate situation.

Several diplomats also said the North Koreans may resent China's growing informal trade relations with South Korea and may, in a sense, be "retaliating" against the Chinese by drawing closer to the Soviets.

One western diplomat said recently that it seemed clear now that China's most difficult foreign relationship was with the North Koreans, who are known for their isolation from much of the world and their ideological rigidity.

The Chinese comment came on the eve of two days of high-level talks on Asia between U.S. and Soviet diplomats in Moscow at which the American side was expected to express Reagan administration concern over what it has described as a significant Soviet naval buildup in East Asia and over the Soviet delivery earlier this year of advanced MiG23 jet fighters to North Korea. About a month ago, three Soviet warships made an unprecedented call at a North Korean port.

Because of the need to develop its economy, China clearly has an interest in a stable Korea and has been encouraging the on-again, off-again dialogue that has taken place between the North and South. The Chinese have expanded informal contact with South Korea, apparently in the hope that the United States and Japan might eventually reciprocate by opening contacts with North Korea. Given their major, and seemingly intractable, trade deficit with Japan, the Chinese also stand to gain from continuing trade, both direct and indirect, with South Korea.

From a position of virtual non-involvement, China has moved to one of actively trying to reduce tensions on the Korean peninsula over the past few years.

"It probably worries the North Koreans every time they see China and South Korea work out a problem . . . ," said a western diplomat, referring to recent incidents in which South Korea agreed to return to China a torpedo boat crew and a crew member of a Chinese naval aircraft whose pilot defected and crashed in South Korea.

The North Korean warming to the Soviets became obvious last year when North Korean leader Kim Il Sung visited Moscow for the first time in 20 years. Equally dramatic was the visit to North Korea on Aug. 13 by a high-level Soviet Politburo member, First Deputy Premier Geydar Aliyev, to celebrate the 40th anniversary of the end of Japanese rule and the victory over Japan in World War II. The Aliyev mission included a Soviet first deputy minister of defense and about 25 to 30 separate government and military delegations.