The White House acknowledged yesterday for the first time it might not be able to close the US military prison at Guantanamo Bay by January as President Barack Obama promised.

Senior administration officials said difficulties in completing the lengthy review of detainee files and resolving thorny legal and logistical questions mean the president's self-imposed January deadline may slip.

Obama remains as committed to closing the facility as he was when, as one of his first acts in office, he pledged to shut it down, said the officials, who spoke on condition of anonymity in order to more freely discuss the sensitive issue.

They said the White House still was hoping to meet the deadline through a stepped-up effort.

The prison in Cuba was created by former president George Bush after the 11 September 2001 terrorist attacks.

But it has since become a lightning rod of anti-US criticism around the globe. There are approximately 225 detainees still being held at the prison.

Obama promised soon after taking office – and many times since – to close the prison, arguing that doing so was crucial to restoring America's image in the world and to creating a more effective anti-terror approach.

But eight months after Obama's pledge and with only four months to go before the January deadline, a number of difficult issues remain unresolved.

They include establishment of a new set of rules for military trials, finding a location for a new prison to house detainees and finding host countries for those who can be released.