TUCSON, Ariz. (AP) _ Machinists at Hughes Missile Systems Co. rejected a contract proposal and authorized a strike unless the company returns to the bargaining table.

Negotiations broke off at 3 a.m. Sunday and the union put the company's ``last, best and final'' offer to a vote. Union officials said 96 percent of those who voted rejected the offer.

Local 933 of the International Association of Machinists and Aerospace Workers had urged the 1,800 Hughes production workers it represents to reject the offer. The old contract expired at midnight Sunday.

Union officials said the offer would imposes a two-tier wage structure and reduce pension and other benefits, including vacation and sick leave. It also restricted workers from bargaining over changes in their medical plans.

Hughes spokesman Jim Gilkerson said the company had not heard from the union, but officials would be ``willing to clarify any items in our last, best and final offer.''

Gilkerson praised the health benefits package and said the workers also would have received a general wage increase in each of the contract's three years, as well as significant lump-sum cash payments in the first two year.