U.S. and Soviet negotiators failed in talks on Friday to reach an agreement covering future Soviet imports of American grain, chief Soviet negotiator Yuri Chumakov said.

He said the latest in several rounds of talks on a multi-million-dollar deal ended with no deal and the two sides would now consult their governments on whether to meet again.Earlier, an official involved in the London talks said they differed on both the duration of a new pact committing Moscow to agreed minimum purchases of American grain and how binding it would be.

"We haven't reached an agreement," Chumakov said.

Anxious to offer its strong farm lobby a guarantee of long-term sales, the United States wants Moscow to guarantee minimum purchases for five years.

Soviet negotiators want more flexibility in case reforms by Kremlin leader Mikhail Gorbachev begin to result in much bigger Soviet harvests. They favor a less binding accord beyond the first year, a negotiator said.

The U.S. side on Thursday balked at agreeing to a draft Soviet proposal calling first for a one-year accord to be replaced later by a five-year non-binding agreement.

"It wouldn't be an agreement. It would just be this nice piece of paper," a U.S. official said.

In the first year Moscow would pledge to buy either nine or 10 million tons depending on whether it bought all grain or included some soybeans and/or soymeal.

A previous U.S.-Soviet grain supply agreement, the largest trade pact of its kind, expired on September 30 and called for annual minimum Soviet purchases of nine million tons.

Earlier talks have been held in Washington and Vienna to try to negotiate a new agreement between the world's biggest importer and exporter of grain.

The Reagan administration had hoped to wrap up a five-year accord in time to give a boost to Republican presidential candidate George Bush before the Nov. 8 election.