WASHINGTON — President Barack Obama’s budget, presented to Congress Monday, seeks more than 300 million dollars to help pay for the closure of the controversial Guantanamo Bay detention facility.

The budget requests 237 million dollars for the acquisition of the Thomson prison in Illinois, where the administration plans to hold dozens of men transferred from Guantanamo Bay.

It also seeks another 73 million dollars to pay for the prosecution of five men accused of planning the September 11, 2001 attacks.

The purchase and upgrade of the Thomson facility is a central pillar in the administration’s plan to close Guantanamo.

The administration wants to transform the Illinois facility into a high-security prison, with one wing set aside to hold former Guantanamo prisoners.

The wing will be administered by the Pentagon, and hold terror suspects facing trial in the United States, but also those the administration plans to hold indefinitely and without charge — less than 100 prisoners in total.

“This budget has funds to acquire, renovate, equip and staff the facility. 170 million to acquire the facility, 67 (million) for renovating, equipping and staffing,” said Lee Lofthus, the chief financial officer at the Justice Department.

He noted that the budget does not come into effect until October 1, suggesting that detainees could not be moved from Guantanamo to the Illinois facility until the final months of 2010.

Republican lawmakers have already opposed funding the transfer of Guantanamo detainees into the United States, but administration officials argue that refurbishing the Thomson facility will add sorely-needed federal prison beds.

The prison has space for 1,600 prisoners and “it’s very expensive to build up a prison and smarter to buy one,” said Lofthus.

The expenditure “is warranted even in the absence of any shift of prisoners from Guantanamo because the Federal Bureau of Prisons needs additional bed space,” added Peter Orszag, director of the White House office of management and budget.

In addition to money for Thomson, the budget seeks 73 million dollars to pay for the transport, detention, prosecution and legal defense costs associated with prosecuting five men accused of plotting the 9/11 attacks, including the self-described mastermind of the 2001 attacks, Khalid Sheikh Mohamed.

Another 200 million dollars is requested for the Department of Homeland Security, to pay for increased security in cities where former Guantanamo detainees will go on trial.

The cost of putting high-profile terror suspects on trial has emerged as a key obstacle to the administration’s plan to prosecute the alleged 9/11 plotters in New York City.

The plan, initially hailed by Democrats, was reportedly scrapped last week after even moderate New York Mayor Michael Bloomberg expressed concern about the projected 200-million-dollar price tag for securing the trial.

The administration has not officially announced a plan to move the trial, but officials acknowledged last week that alternative venues were being considered.

While the administration has pledged to push ahead with plans to close Guantanamo, where 192 men are still being held, the budget also includes a request for an additional 350 million dollars for the Pentagon for detainee operations.

The money is requested under the “overseas contingency operations” fund, and is to “be used to finance all aspects of detainee operations, either at the Guantanamo Bay facility or at another site,” the Pentagon said.