Lloyd’s of London is asking a federal court to block a claim by oil company BP seeking damages against its Deepwater Horizon partner, Transocean, over oil spewing from the bottom of the Gulf of Mexico.

Clean up operations near Venice, La.

Lloyd’s underwriting subsidiaries and other insurers providing $700 million of coverage to Transocean, the owner of the oil rig, filed papers in a Houston court, arguing that the policies provided to their client preclude claims related to environmental damage caused by the leaking well, according to Reuters.

Citing court documents, Lloyd’s argues that Transocean’s contract with the petroleum company only makes it liable for environmental damage caused by spills from the rig and not the well, which is the cause of a massive oil leak threatening several Gulf states.

On April 20, an explosion on the Deepwater Horizon rig killed 11 workers and touched off a leak in the oil well at the ocean’s floor.

Reuters reported that BP said it lodged a claim against the insurers, but declined further comment.

The news services states that if BP is awarded the full $700 million, it would only be a small fraction of the cost of a massive cleanup effort. UBS analysts currently put that cleanup cost estimate at $12 billion.