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.”

The arrest warrant follows 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.”

The Government figure for the number of Britons killed in the Nairobi shopping mall attack was reduced from six to five earlier today.

The Foreign Office said one of the victims previously thought to have been a UK national was Kenyan.

However, a spokeswoman 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 by al-Shabab militants on the Westgate shopping mall is expected to rise from the current level of 67, with more than 60 people apparently yet to be accounted for.

Somali president Hassan Sheikh Mohamoud warned such attacks may become more frequent as al-Shabab attempts to reassert its dwindling power base.

He told Channel 4 News: “Some people sometimes mix the issues that Shabab want an Islamic state in Somalia – that’s not true. Shabab want a unified (one) state all over the world.

“They do not believe in borders, they do not believe in sovereignty, so their theme is global, it’s not even regional.”

He warned: “They may do this act again and again.

“The act is of a dying organisation. You see Shabab now they control remote parts of Somalia, where they are still using as their training territory, where they are still using as a bomb factory, where they still have in the training centre special units that brainwash the young people from within Somalia, out of Somalia. So, these types of things will continue.”

The full “forensic audit” of the Nairobi shopping mall terror attack will take at least seven days to complete, the country’s interior minister has said.

Joseph Ole Lenku said it was still not known whether there were any Britons or Americans among the al Qaida-linked militants or whether any of them was a woman.

•Credit (except headline): Daily Mirror UK. Photo shows Samantha Lewthwaite alias White Widow.