Suspense over a possible strike at U.S. refineries continued as the United Steelworkers union prolonged talks with companies on Monday for a new contract involving thousands of workers across the country.

The current contract covers about 24,000 workers, according to the Associated Press. It includes 86 refineries, chemical plants, pipelines and terminals. The contract expired Sunday but the talks have been extended to reach an agreement that would avoid a strike.

The latest announcement from the union is that it hasn't received new proposals from Royal Dutch Shell Plc who is leading the talks, according to USW spokeswoman Lynne Baker.

We are still working under a rolling 24-hour contract extension and will continue to bargain till we reach an agreement or either party terminates the contract, Baker said according to the agency.

The companies involved include Royal Shell , Exxon Mobil Corp., Valero Energy Corp., BP Plc,and Chevron Corp.

The talks began Jan. 20.

Valero Energy Corporation