U. S. officials have revealed that Chinese discomfort with American banking procedures delayed the signing of a crucial claims and assets agreement for more than two months, suggesting trouble-some future legal snarls in U. S. Chinese trade.

A concerted effort by American officials travelling with Commerce Secretary Juanita Kreps in China and outspoken support for an agreement from Chinese Vice Premier Deng Xiaoping (Teng Hsiao-ping) appeared finally to override the obstacles and allow this morning's signing of the agreement.

The solution of the 30-year-old issue of American property seized in China and Chinese bank accounts frozen in the United States is a vitalstep toward a trade agreement, a lowering of high tariffs on Chinese goods and a substantial increase in trade between the world's most populous nation and the richest.

American officials outlined what caused the delay after the claims agreement supposedly was completed and initialed March 1. The officials said the Chinese began to wonder if they actually would be able to secure the bulk of the estimated $80.5 million in assets frozen in U. S. banks without Washington's continued intervention.

Peking had agreed to pay $80.5 million to owners of seized American property - a return of about 41 cents on the dollar. To get their money back in the form of unfrozen assets they might have to confront great reluctance from American banks to release information about their depositers.

Although the Chinese eventually swallowed their objections, and armed with some minor American assurances, signed the agreement, their experience suggests that many more complaints may be pouring out of Peking about the legal difficulties of trading with Americans.

At stake is an estimated $1.5 billion in Sino-American trade this year and perhaps $6 billion to $8 billion by 1985. The Kreps mission came here to negotiate a general trade agreement which itself is lagging behind because of Chinese unfamiliarity with the rigors of U. S. law. Even translation is difficult.

"Try rendering 'subject to' into Chinese," one veteran U. S. interpreter said.

Kreps has been able to take a number of small steps toward greater trade, most of them well prepared before her party arrived here. Agreements on exchange of oceanographic and meteorological information and on the holding of two American trade exhibitions in China in 1980 have been signed. Comp licated negotiations over maritime and aviation agreements have begun. The two countries may even be able to arrange charter flight exchanges before a final aviation agreement is signed.

If an overall trade agreement, covering such matters as patent protection and resolution of disputes, can be concluded, and if agreement on limits on Chinese textile sales in the United States can be reached, then the Carter administration would be free to ask Congress for most-favored-nation trade status for Peking. This would substantially cut tariffs on Chinese goods and give Peking more hard cash to buy adanced U. S. equipment.

Several steps remain, however, and officials advise caution in predicting rapid trade growth. They point to some Chinese industrial readjustments and the delay in signing a claims pact initialed by Treasury Secretary Michael Blumenthal in Peking March 1.

In the Blumenthal agreement, the Americans had offered some help to the Chinese in securing their frozen assets, but Peking declined. Then, after initialing the agreement, Peking signaled problems and asked Washington to find out from the American banks exactly what Chinese depositers had their accounts frozen by President Truman's order in 1950 and how much the accounts held. The Americans replied that they could only ask the banks to volunteer information.

In other communist nations that have negotiated claims agreements with Washington, individual citizens with U. S. assets usually have had no hope of recovery unless they revealed themselves to their government. Some apparently have concluded that the chances of political reprisal for harboring secret funds too great to risk. Officials think some small amounts of the frozen Chinese accounts may never be recovered because of this.

Washington responses to the Chinese requests promised only to pass on information to the U. S. banks, who would be ruled by their won confidentiality rules. The agreement was signed, but many experts wonder if the Chinese will recover an amount even approaching $80 million.