An international arrest warrant has been issued for British terror suspect Samantha Lewthwaite, who was married to one of the July 7 bombers.
Interpol said it was issuing the “Red Notice” for the arrest of Lewthwaite - dubbed the “White Widow” - at the request of the Kenyan authorities.
The warrant relates to charges of being in possession of explosives and conspiracy to commit a felony dating back to December 2011.
Interpol secretary general Ronald Noble said: “By requesting an Interpol Red Notice, Kenya has activated a global ‘tripwire’ for this fugitive .
“Through the Interpol Red Notice, Kenyan authorities have ensured that all 190 member countries are aware of the danger posed by this woman, not just across the region but also worldwide.”
There has been intense speculation linking Lewthwaite, 29, to the Nairobi shopping mall attack by Islamist militants from the al Qaida-linked al Shabab group.
The Kenya authorities have said forensic experts are working to establish if any of the attackers was female after receiving reports that a British woman was involved.
Lewthwaite - who is believed to use the alias “Natalie Webb” - had previously only been wanted at national level for the possession of a fraudulently obtained South African passport.
Mr Noble said her case highlighted the “invisible threat”’ posed by terrorists and criminals travelling internationally using illicit passports.
“Every year hundreds of millions of individuals are boarding international transport and crossing borders without having the authenticity of their travel or identity document checked,” he said.
“This dramatically compromises our ability to effectively screen and identify at airports and land crossings those individuals who could be suspected criminals and terrorists.”
A Red Notice - or internationally wanted persons alert - notifies police forces around the world that an individual is wanted by an Interpol member state and requests the suspect is placed under provisional arrest pending extradition.
Earlier, the Foreign Office said the number of Britons killed in the attack on the Westgate shopping mall attack has been revised down from six to five.
A spokeswoman said one of the victims previously thought to have been a UK national was now known to be Kenyan.
However, she warned that the casualty figure could still rise further as the authorities continue to comb the scene.
“We can now confirm that on present information five British nationals have been killed in the recent terror attacks in Nairobi,” she said.
“One individual previously thought to be British is a Kenyan national. Our thoughts are with his family and with the friends and family of all of those who have died during this difficult time.
“We have no information at this time that any further British nationals have been killed, although we cannot rule out the potential for further British casualties and we continue to stay in close contact with the Kenyan authorities as their investigations continue.”
The death toll from the attack is expected to rise from 67 - including 61 civilians and six members of the Kenyan security forces - as the Kenyan authorities scour the wreckage of the mall.
Five terrorists also died in the four-day stand-off and the Kenyans say they are holding 11 suspects in custody in relation to the attack - including at least seven who are thought to have been arrested at the airport.
International forensic experts, including teams from Scotland Yard, the United States, Israel, Germany and Canada, are helping sift through the debris for clues.