Transocean Limited, the company that owned the drilling rig that exploded in the Gulf of Mexico last year, is arguing that its contract with BP shields it from having to pay for the largest offshore spill in the nation's history.

In court documents filed Tuesday, Transocean Ltd. claims a contract it signed with BP PLC., to drill the well indemnifies Transocean from paying fines or for damages.

A trial designed to assign shares of fault to the companies is scheduled to start Feb. 27. The trial also will aim to determine whether rig owner Transocean can limit what it pays claimants under maritime law.

Transocean says BP broke its contractual promises by suing Transocean.

BP did not immediately comment on the allegations.