British spies are expected to find out whether they will face charges on Thursday over their alleged complicity in the torture of terror suspects.
Several MI5 and MI6 agents are understood to be at the centre of criminal investigations into the treatment of former detainees including UK resident Binyam Mohamed.
Prisoners at Guantanamo Bay claim British security and intelligence officials colluded in their torture and abuse while they were held at the controversial detention centre.
The Crown Prosecution Service will issue a statement "announcing a number of decisions in relation to the investigations into the alleged ill-treatment of detainees".
The announcement comes after human rights campaigners condemned the US government's ongoing failure to close Guantanamo, 10 years after the arrival of the first detainees.
An inquiry into British complicity in torture and rendition was due to begin in the wake of the police investigation.
Foreign Secretary William Hague has stressed the Government's commitment to "drawing a line" under the alleged involvement of intelligence agencies in the torture of terror suspects held overseas.
But human rights groups and lawyers are refusing to give evidence or attend any meetings with the inquiry team because it does not have "credibility or transparency".
A number of British Muslims have complained that they were questioned by agents after being tortured in Pakistan, Bangladesh, Afghanistan and Guantanamo.
Others say they were tortured in places such as Egypt, Dubai, Morocco and Syria, while being interrogated on the basis of information that could only have been supplied by the UK.
In November 2010, Justice Secretary Kenneth Clarke announced that secret payouts to 16 former detainees at Guantanamo were being made to pave the way for the inquiry into allegations of torture.
Mohamed, Bishar Al Rawi, Jamil El Banna, Richard Belmar, Omar Deghayes, Moazzam Begg and Martin Mubanga were said to be among those receiving settlements.
Mohamed was granted refugee status in Britain in 1994 after seeking asylum from Ethiopia.
He travelled to Pakistan in 2001 - the year he converted to Islam - and was arrested there a year later on suspicion of involvement in terrorism, before being "rendered" to Morocco and Afghanistan.
After being subjected to alleged torture by his US captors, he was sent to Guantanamo Bay in 2004. However, in October 2008, the US government dropped all charges against him.
Mohamed was released and returned to Britain in February 2009.
In a rare speech on the use of secret intelligence in November, Mr Hague acknowledged that Britain's reputation had been damaged by claims that MI5 and MI6 officers had been complicit.
"The very making of these allegations undermined Britain's standing in the world as a country that upholds international law and abhors torture," he said.
Both the detainee inquiry under Sir Peter Gibson and Green Paper proposals to enable the greater use of secret intelligence material in court cases have prompted controversy.
The Green Paper has been criticised by human rights groups who warned that it would lead to greater secrecy in the justice system, making it more difficult to hold the authorities to account for alleged abuses.