WASHINGTON: Six months before President Barack Obama's targeted deadline to shutter Guantanamo Bay jail, mounting obstacles and the complexity of the task are raising new doubts it will close by January.

Since Obama signed an executive order on January 22 to close down the controversial prison camp, only 11 detainees have been freed and one has been transferred to the United States to face trial in a civilian court.

Most of the remaining 229 "war on terror" prisoners at the US naval base in southern Cuba have been held for more than seven years without charge or trial.

On Monday, senior administration officials said a task force reviewing detention policy would need another six months to complete a report, which had been due Tuesday, on its efforts to close Guantanamo.

And a separate task force examining interrogation policy will need another two months to complete its report.

Launched in 2002 by then-president George W. Bush, Guantanamo has been a thorn in Obama's side, with lawmakers barring the transfer of any of the detainees to US soil until they receive a clear plan on their fate from the administration.

And US allies, despite initially clamoring for the notorious jail to be closed, have been cool toward hosting the terror suspects.

"These are hard, complicated and consequential decisions," a senior administration official told reporters, speaking on condition of anonymity.

Saying the January target for closure of the prison camp remained a "goal," another official said the detention policy task force was seeking to "put together a comprehensive plan, deal with every single element... and to move to the Congress with those plans and determinations and seek their support."

While recognizing that Congress, including lawmakers from Obama's own majority Democratic Party, had temporarily slowed down the process, the administration remains confident it can meet the self-imposed deadline.

A third task force is thus examining the individual cases of each Guantanamo detainee in order to determine which ones can be freed or tried and, if so, in what type of court.

With more than half of the cases reviewed six months ahead of the January target date, the task force has already authorized the transfer of over 50 detainees and sent a "significant number" of other cases to prosecutors for charges to be brought, another official said.

But the official added it was "a significant undertaking and it's taking us some time because the information was spread out between the agencies that have obtained them... over the last eight years."

The task ahead will be further complicated if the administration decides some of the detainees have to held indefinitely because they are too dangerous to be released, but there is not sufficient evidence to charge them.

Such a controversial move is loudly opposed by the leftwing and has not yet been approved by the White House, officials say, and would not be put into effect without the agreement of Congress.

Such lingering questions could well stymie even further the moves to empty the cells in Guantanamo, and close the jail for good.

"We want to get this right and not to have another multiple years of uncertainty around these issues, but rather be able to present to the Congress and American people a plan with legal foundation," one of the officials stressed.