HUNTINGTON, W.Va. (AP) _ The United Mine Workers ordered 2,000 West Virginia miners onto the picket line Tuesday, doubling in size the union's strike against the nation's coal operators.

The two sides appeared no closer to resolving the differences that triggered the strike May 10, when the UMW called out 2,000 miners at 10 mines in Indiana and Illinois.

''This is going to be a long strike,'' said Johnny Miller, an employee of Hobet Mining Co.'s No. 7 mine near Madison. His local joined the picket line at 8 a.m. Tuesday. ''You'll probably be talking to us when the snow's flying.''

The coal operators' chief negotiator, CONSOL Inc. Chairman B.R. Brown, called for a return to the bargaining table. Union President Richard Trumka said the strike will continue to expand ''unless coal operators ... agree to keep their word.''

Since they signed their last contract in 1988, the two sides have wrangled over the meaning of a provision that promises the union three out of every five new jobs.

According to the union, the provision applies to members of the Bituminous Coal Operators Association and their sister companies that operate as nonunion. The coal operators have maintained that the provision applies only to those entities that actually signed the agreement.

The two sides have been trying since November to reach agreement on a new contract covering 60,000 miners in Ohio, Pennsylvania, West Virginia, Kentucky, Illinois and Indiana.

The old contract ran out Feb. 1. On Feb. 2, miners went on strike against Peabody Holding Co., the nation's largest coal producer. The walkout ended March 3 with an agreement to extend the contract 60 days. But talks broke down again before the extension expired May 3.