The White House is in the "final stages" of a plan to close the contentious Guantanamo Bay detention facility and submit it for review by lawmakers, spokesman Josh Earnest said Wednesday.

President Barack Obama made the closure of the controversial offshore prison a priority when he took office in 2009, but the plan has faced numerous setbacks, including Congress blocking the transfer of detainees to US prisons.

"The administration is in fact in the final stages of drafting a plan to safely and responsibly (close) the prison at Guantanamo Bay and to present that to Congress," Earnest said.

"That has been something that our national security officials have been working on for quite some time, primarily because it is a priority of the president."

The operation in Cuba is not an effective use of government resources, Earnest told reporters.

"This is complicated work, but we have made a lot of important progress," he added.

Cuba sees US 'occupier'

The broader Guantanamo US military facility is also opposed by the Cuban government, with which the US recently restored diplomatic relations. Cuba says the United States is illegally occupying its land.

Cuban Foreign Minister Bruno Rodriguez called for the return of the territory to Cuba while in Washington Monday.

Secretary of State John Jerry said at the time that the US had no plans to alter its Guantanamo lease treaty. Cuba however says there is no lease, and that there has been none with communist Cuba in a half century.

Washington has slowly been sending prisoners back to their home countries or to third countries, something that needs to continue if the facility is to shut, Earnest said.

Other detainees need to be prosecuted or reviewed for release, he said.

Transfers and opposition

The United States said in June a group of six Yemeni detainees were transferred to Oman. While a new special envoy tasked with closing the prison was also recently appointed by Kerry.

Lee Wolosky, a lawyer who worked under both presidents Bill Clinton and George W. Bush, was chosen as the State Department's Special Envoy for Guantanamo Closure.

The post, which tries to manage the transfers of detainees, had been vacant since December.

But the transfer of detainees to the United States is opposed by Congress, and some lawmakers have tried to halt all transfers out of Guantanamo, saying the releases could lead to more attacks.

In June, the Senate endorsed a bill that strengthens restrictions on the closure of the Guantanamo prison, a plan Obama has threatened to veto.

Earnest said he was concerned about seeing Congress "repeatedly impede the effort to close the prison at Guantanamo bay despite bipartisan agreement that closing the prison is actually in the national security interest of the United States."

The military prison opened in January of 2002 shortly after the September 11, 2001 attacks in the United States.

After reaching a peak of 680 prisoners in 2003, there are 116 inmates remaining.

Just under half of the detainees remaining have been cleared to leave but have yet to be resettled or repatriated.

Detainees have been slowly tried by military commissions in Guantanamo Bay in cases that have stretched over years. Many cases remain stalled in lengthy pretrial stages.

The Obama administration has pushed for trial of terrorism suspects in federal court, saying the venue leads to justice much faster than military tribunals.