China disclosed today it was calling off talks on normalizing relations with its principal international adversary, the Soviet Union.

The talks, begun four months ago in Moscow, apparently had not made much progress but were seen by diplomats here as providing a forum that might one day significantly alter global power balances.

A two-sentence statement by a Chinese Foreign Ministry spokesman today blamed the Chinese action on the Soviet invasion of Afghanistan and gave no clear indication under what circumstances the talks could resume.

"The invasion of the Soviet Union into Afghanistan threatens world peace and China's security, creating new obstacles for normalizing relations between the two countries," the Chinese spokesman said. "Under such circumstances it goes without saying that it is inappropriate to hold Sino-Soviet talks."

Peking had apparently hoped to use the talks to improve trade with Moscow and perhaps reduce tension on their long mutual border so that Chinese military expenditures could be diverted to the limping civilian industry.

The first round of talks, reopening a dialogue after 15 years of enmity and occasional border conflict, ended Nov. 30 in Moscow and was scheduled to be continued here at an undisclosed date. Peking had made it clear that it expected only small, technical improvements in state-to-state relations with Moscow and had continued its almost daily propaganda barrage against the Soviets as global aggressors.

Meanwhile, a six-man U.S. congressional delegation left China today after three days of talks that covered the crises in Afghanistan and Iran.

Rep. Lester Wolff (D-N.Y.), chairman of the House subcommittee on East Asia and the Pacific and leader of the delegation, said China is considering buying some U.S. grain available following the U.S. action halting the shipment of 18.7 million tons to the Soviet Union in response to its Afghan intervention.

Wolff said China planned economic and military aid to its ally Pakistan, which has a 1,200-mile border with Afghanistan.

He said the Chinese defended their decision to hold off support for sanctions against Iran to win release of the American hostages in Tehran and "made clear their feeling that the U.S. may be focusing too much on short-range concerns."

Wolff also said he pressed the Chinese on the issue of Pakistan's continued development of a nuclear weapon, "which represents a serious threat to the stability of the region."

He said the two sides agreed on the need to defend Thailand against any Vietnamese attack. The Chinese mentioned their dispatch of "volunteer" troops to Korea in 1950 and their attack on Vietnam last year during the discussion of Thailand.

In an interview yesterday, Wolff said he raised the possibility of a Soviet invasion of Iran that "threatened the oil fields."

The Chinese said they welcomed the strong U.S. statements on this threat, but added that "China was not in a position to militarily support Iran other than to keep busy the million (Soviet) troops on their border."