http://news.bbc.co.uk/2/hi/middle_east/3680120.stmThe US has dismissed reports from Iraq's justice ministry that one of two female scientists held in a US-run prison is to be released.
A US source told the BBC that both prisoners were in the physical and legal custody of the Americans and would not be freed imminently.
Militants have reportedly killed two American hostages and are threatening to kill a third, Briton Kenneth Bigley.
They had demanded the release of all Iraqi women held in US-run prisons.
The US says it is only holding two women prisoners - Rihab Rashid Taha and Huda Salih Mahdi Ammash - and that it has no knowledge of any plan to release them.
The UK government told the BBC there was no request by anyone at any level in the government for the women to be freed.
"That would be tantamount to dealing with terrorists," a Downing Street spokesman said.
'Not a threat'
The first US hostage, engineer Eugene Armstrong, 52, was killed on Monday and 24 hours later the group claimed to have killed a second American, Jack Hensley.
A decapitated body, thought to be that of Mr Hensley, has been found in Baghdad, but it has not been formally identified.
RIHAB RASHID TAHA
Nicknamed Dr Germ
Worked on Saddam Hussein's biological weapons programme
Accused of producing anthrax
Educated in UK's University of East Anglia
Surrendered to US forces in May 2003
Considered important target, but not on US list of 55 most wanted Iraqis
Iraq's women scientists
Iraq's Justice Minister Malik al-Hassan told the BBC that he supported the release of Dr Taha, a biological weapons scientist nicknamed Dr Germ, as part of a general review of which prisoners should remain in custody.
"This subject has been under discussion for a month. We set up committees and they have been meeting for more than 21 days. All this has nothing to do with the kidnapping," he said.
Dr Taha is said to have carried out top-secret work during the 1980s on germs that cause botulism poisoning and anthrax infections.
The second woman, Dr Ammash, "may be released soon", the Iraqi justice ministry said.
She is a biotech researcher known as Mrs Anthrax and Chemical Sally, who was on the US military's list of the 55 most-wanted members of Saddam Hussein's regime.
An Iraqi spokesman said Dr Taha was no longer considered a threat to national security.
British family's hope
The family of hostage Kenneth Bigley, 62, had welcomed the Iraqi suggestion of a proposed prisoner release.
Profile: Tawhid and Jihad
Hostages: Facts and figures
Mr Bigley's brother Paul told BBC radio: "Hopefully they
will pick this up on the media, and show that they have a gram of decency in them by releasing Ken."
The three hostages were kidnapped on Thursday by militants claiming to be from the Tawhid and Jihad group, headed by al-Qaeda suspect Abu Musab al-Zarqawi. The group claims to have killed at least six hostages in Iraq.
Gruesome video footage was released on Monday showing Mr Armstrong being killed by a masked man - said by the CIA to be Zarqawi. Mr Armstrong's body was later recovered.
"The British prisoner will get the same fate if the British government doesn't do what it has to," said a statement on an Islamist website.
More than 100 foreigners have been abducted in Iraq over the past 17 months, as part of efforts to destabilise the US-backed interim government and to drive out foreign troops.
They include two French journalists who were abducted last month and two female Italian aid workers who were seized with two Iraqi colleagues on 7 September.
Tawhid and Jihad is considered to be the most ruthless of the hostage-takers.