UPDATE 1-U.S. Coast Guard finds new leak in undersea well

(New throughout, adds details from Coast Guard briefing)

HOUSTON, April 28 (Reuters) - The U.S. Coast Guard on Wednesday said it has found a new leak beneath the site of last week’s deadly offshore drilling rig explosion, and said five times as much oil was leaking as previously estimated.

At a briefing with reporters, U.S. Coast Guard Rear Admiral Mary Landry said London-based BP Plc BP.L, owner of the leaking well and financially responsible for the cleanup, told U.S. officials of a new leak on a well 5,000 feet (1,525 metres) under the sea off Louisiana.

“BP has just briefed me of a new location of an additional breach in the riser of the deep underwater well,” Landry said.

The leak, which has created a massive oil slick that could hit the Gulf Coast this weekend, is estimated at 5,000 barrels per day -- up from the Coast Guard’s previous estimate of 1,000 barrels per day.

“We have urged BP to leverage additional assets,” Landry said, adding that President Barack Obama has been briefed on the situation.

Eleven workers are missing and presumed dead after the worst oil rig disaster in almost a decade. Swiss-based Transocean Ltd's RIGN.SRIG.N Deepwater Horizon rig sank on April 22, two days after it exploded and caught fire while finishing a well for BP about 40 miles (64 km) southeast of the mouth of the Mississippi River. (Reporting by Chris Baltimore; Editing by Eric Walsh)