March 17 (Reuters) - BP on Tuesday barred about

800 United Steelworkers members from its 440,000 barrel-per-day

refinery in Whiting, Indiana starting at 12:00 a.m. on March 19

after negotiations with the union broke down.

The company canceled its 24-hour rolling contract extension

and issued the lockout notice after the union rejected key

proposals that BP says are critical to the refinery's long-term

sustainability.

Maintenance employees were told not to report after March

17, while other USW-represented workers will report through

March 18.