The military trials for Guantanamo detainees have been much criticised
US President Barack Obama is expected to announce on Friday that he is reviving military trials for some of the detainees at Guantanamo Bay.
But legal rights for defendants facing the military commissions will be significantly improved, officials said.
President Obama halted the trials as one of his first acts on taking office in January, saying the US was entering a new era of respecting human rights.
The decision to revive the military trials has angered civil rights groups.
There are currently 241 detainees still at the US base in Guantanamo Bay, Cuba.
President Obama has pledged to close the camp by January 2010.
Administration officials told journalists that President Obama would announce plans to restart the military commissions - but with improved rights for detainees.
They are reported to include restrictions on hearsay evidence; a ban on evidence obtained by cruel treatment; giving detainees more leeway to choose their own lawyers; and protecting detainees who refuse to testify.
President Obama is expected to ask for a further four-month delay for the trials so that the new procedures can be implemented.
Some rights groups reacted with dismay to the news. They campaigned throughout the Bush administration for the military trials to be scrapped.
"It's disappointing that Obama is seeking to revive rather than end this failed experiment," said Jonathan Hafetz of the American Civil Liberties Union.
"There's no detainee at Guantanamo who cannot be tried and shouldn't be tried in the regular federal courts system."
President Obama himself had criticised the military commission system during his election campaign, describing it as "an enormous failure".
But, his aides pointed out on Thursday, the president never rejected the possibility of using military commissions altogether if they could be made fairer.
They highlighted legislation he supported as a senator in 2006 which was intended to do just that.
The BBC's Adam Brookes in Washington says the president may have decided that trying detainees such as Khalid Sheikh Mohammed - the man who allegedly planned 9/11 - in a civilian court in the US would be simply too complex and too difficult.
It is thought that only around 20 of the current detainees are likely to be tried through the revived military commissions, our correspondent says.
The remaining Guantanamo detainees are expected to either be released, transferred to other countries or tried by civilian prosecutors in US federal courts.