BBC: BP is being allowed to keep the cap on its damaged well shut for another 24 hours, says the US official in charge of the Gulf of Mexico oil clean-up. In a letter to BP, Adm Thad Allen expressed concern about a "detected seep" on the sea floor near the well and other "undetermined anomalies". US Oil Spill Damage assessment Alaska heals from 1989 spill Which way forward for BP? Ways BP has tried to stop the leak The firm has pledged to monitor the sea floor for …