Owners of an oil rig that exploded last week in the Gulf of Mexico say they are fully covered by insurance.

The Deepwater Horizon, owned by Swiss group Transocean, was drilling a well for BP on April 20 when a blast ripped through its structure, leaving 11 workers missing, presumed dead.

The remains of the rig now lie 450m northwest of the drill centre, where more than 170,000 litres of oil a day is leaking into the gulf.

Transocean says rig is insured for total loss coverage and for wreck removal totalling $US560 million ($605.5 million).

BP is understood to operate a number of captives covering the insured value of the rig. Munich Re is expected to front about $US100 million ($108 million) in claims.

Hannover Re says it is anticipating a €40 million ($57.1 million) claim from the disaster.