Negotiators for 18,000 striking steelworkers in Minnesota and upper Michigan asked United Steelworkers President Llyod McBride to seek a better incentive pay offer in hopes of avoiding a winter-long strike.

The 11-week-old strike has shut off 60 per cent of taconite supplies to the nation's steel mills.

The steel companies's first offer was rejected Monday by 80 local union negotiators in a 3 1/2 hour meeting. A five-man committee tried to draw a counterproposal Monday night but then referred the offer back to McBride.

McBride presented the companies offer to negotiators at a weekend meeting in Virginia. Minn., saying it probably was the best offer the companies would be willing to make until next spring. But negotiators said it wasn't enough and a local union president labeled it a sellout by national union leaders.

It was the first time steel firms had discussed incentive pay with miners, although steel mill workers get incentive pay.

Union negotiators protested that the offer would give incentive pay to only about 75 per cent of the work force and would not go into effect until Nov. 1, 1979.

At that time, miners would be changed over from a 30 cent-an-hour show-up bonus to incentive pay would amount to above 73 cents an hour and the overall increase would be about 55 cents an hour.

The negotiators also complained the incentive pay offered for miners would be only about two-thirds of that received by steel mill workers.

They also said about 25 percent of the striking steelworkers , especially lower-level nonproduction workers, would not get the incentive pay under the plan and on Nov. 1. 1979, their 30 cent hourly show-up pay would drop to 10 cents an hour.