Guantanamo detainees
As part of the relocation plan, some of the foreign detainees will be sent back to their countries while the more dangerous ones will be kept in a US-based prisonREUTERS/U.S. Department of Defense/Petty Officer 1st class Shane T. McCoy/Handout/Files

President Barack Obama has rejected as too expensive a Pentagon estimate for relocating the Guantanamo Bay detention centre to the US. Pentagon's estimate for the project crosses half a billion dollars.

This development is a setback for the US president who was keen to submit the plan to Congress before his tenure in the Oval Office ends. The Wall Street Journal reported that the Pentagon estimate would require as much as $600m (£398m) to close the facility, including a one-time capital investment of approximately $350m in construction costs, according to officials familiar with the plan that has not been released publicly.

Obama has directed the Pentagon to concentrate on reducing the overall operating costs of the new facility in the US and not focus as much on the one-time construction expenses, the report said.

Closing the facility was one of Obama's 2008 campaign promises and he hoped to shut it down by the end of his first year in office. However, legal and political hurdles continue to impede the plan as Congress is not keen to bring detainees, most of who were involved in terrorist activities, to the country.

The report quoted White House press secretary Josh Earnest as saying that keeping the facility open is "not an efficient or effective use of taxpayer dollars when you consider the alternatives that are available". Obama too referred to it as a recruitment pool for terrorists and a heavy expense for the US government.

Hillary Clinton, before stepping down as secretary of state in 2013, sent the president a memo commending his efforts to close down the overseas prison. "I remain a strong advocate of your policy to close the Guantanamo Bay detention facility (GTMO) responsibly and to ensure U.S. detention policy and practice for terrorism suspects are consistent with U.S. values and do not strengthen our enemies," Clinton wrote in the memo, which was obtained by the Huffington Post through a request under the Freedom of Information Act.

She went on to list strategies by which the closure could be taken forward. "We must signal to our old and emerging allies alike that we remain serious about turning the page of GTMO and the practices of the prior decade," she wrote, referring to the camp's criticised policies, torture programmes and interrogation practices prevalent in the Bush-era.

The Pentagon has already sent a team to assess prison facilities in the country that could house the detainees. These include two military prisons — one at Fort Leavenworth, Kansas, and another at the Navy brig at Charleston, South Carolina. The maximum security prison ADX Florence in Colorado and Colorado State Penitentiary were also on the list.