The Guardian reports:

BP’s new cap over its damaged Gulf of Mexico oil well may not have been as successful as the company had hoped after engineers detected seepage and a possible methane gas leak on the seabed.
Admiral Thad Allen, who is in charge of the US government’s response to the disaster, has written to BP demanding answers to “undetermined anomalies at the well head”. He ordered BP to provide a plan for reopening the well by 1am today (BST).
In a letter to BP’s managing director, Bob Dudley, he said: “When seeps are detected, you are directed to marshal resources, quickly investigate, and report findings to the government in no more than four hours.
“I direct you to provide me a written procedure for opening the choke valve as quickly as possible without damaging the well should hydrocarbon seepage near the well head be confirmed.”
BP has yet to respond to Allen’s letter.