The US Coast Guard is monitoring conditions on the ENSCO 8506 semisubmersible drilling rig which began taking on water into a ballast tank after being hit by heavy seas.

The rig is in 3,800-ft (1,158-m) waters in the Gulf of Mexico more than 100 mi (161 km) south of Galveston, Texas, says the Coast Guard.

The ballast pumps on the rig are keeping up with the water inflow and the rig is on an even keel and stable without an emergency disconnect from the riser, says the USCG. Preparations are for a typical disconnect if that is necessary to facilitate repairs. Conditions yesterday afternoon were 20 knot sustained winds and 12-ft (3.7-m) seas.

There are no reports of injury or pollution.