NEW ORLEANS – The federal government Monday allowed BP to keep the cap shut tight on its ruptured Gulf of Mexico oil well for another day despite something seeping near the sea floor.

The Obama administration's point man for the spill, retired Coast Guard Adm. Thad Allen, said early Monday that the company promised to watch closely for signs of new leaks around the mile-deep well, which has stopped gushing oil into the water since the experimental cap was closed Thursday.

Late Sunday, Allen said something was detected seeping near the broken oil well and demanded in a sharply worded letter that BP step up monitoring of the ocean floor. Allen didn't say what was seeping. White House energy adviser Carol Browner told the CBS "Early Show" seepage was found less than two miles from the well site.

The concern all along — since pressure readings on the cap weren't as high as expected — was a leak elsewhere in the well bore, meaning the cap may have to be reopened to prevent the environmental disaster from becoming even worse and harder to fix. An underground leak could let oil and gas escape uncontrolled through bedrock and mud.