Chrysler Corp. and the striking United Autoworkers union yesterday broke off contract negotiations until Monday, a move expected to cause heavy losses and layoffs among many of Chrysler's 8,000 supply firms nationwide, industry sources said.

The four-day strike has shut down 50 Chrysler plants in 15 states and Canada, idling 70,000 American workers and 10,000Canadians in a dispute that focuses on wages, benefits and job security.

"We have not found the formula. We are still apart on the key issues, including profit-sharing and job security," UAW President Owen F. Bieber said in Detroit. The company had no comment.

Chrysler will lose an estimated $50 million a week during the strike, according to industry analysts, but an extended strike also would cause heavy layoffs in auto supply firms because Chrysler uses outside sources for 70 percent of its parts.

The UAW's key demand that Chrysler agree to "parity" with the contract at General Motors Corp. and Ford Motor Co. has not been met, Bieber said. GM and Ford workers have higher wages, receive profit-sharing bonuses that have added $500 to $1,500 yearly to their paychecks and have a job-security fund for retraining and relocation in the event of layoffs.

But Chrysler, recovering from the brink of bankruptcy, has said that it cannot afford to meet all the UAW's demands.

"We need something special that reflects the sacrifices our members made during the lean years," Bieber said, referring to $1.1 billion in concessions made by union members at Chrysler between 1979 and 1982.