Britain and South Africa both issued new passports to Samantha Lewthwaite in the months before she went on the run, The Daily Telegraph can disclose. Lewthwaite, the widow of the one of the July 7 suicide bombers, received a new British passport in 2011 from the British High Commission in South Africa's capital, Pretoria.
Days earlier, on January 31 2011, Lewthwaite had also been given a South African passport in the name of Natalie Faye Webb, a nurse then living in Essex whose identity she allegedly stole.
Naledi Pandor, the South African home affairs minister, insisted this document was cancelled "in February 2011" and placed on an Interpol "stop list". That should have alerted all 192 members of Interpol to detain anyone found carrying the passport.
Instead, the Kenyan authorities gave Lewthwaite new tourist visas - or renewed old ones - on five separate occasions: February 26; March 28; May 3; August 25; and November 21. All these stamps were placed in the supposedly cancelled South African passport. The last visa was issued just weeks before Lewthwaite went on the run in December 2011.
By then, she was a suspected member of a terrorist cell which was allegedly planning Christmas bomb attacks on hotels and shopping centres. Lewthwaite has now evaded arrest for almost two years.
She was recently named in connection with the Westgate shopping mall attack in Nairobi that killed 67 people, including six Britons, last month. "This clearly points to a failure of collaboration between international organisations," said Valentina Soria, a security analyst at IHS Jane's.
"It also shows that the British authorities missed some very important pieces of information - intelligence that would have shown she had become involved in terrorist activities."
Kenyan police questioned Lewthwaite in December 2011, but were satisfied she was a genuine South African tourist when she showed them the passport that was the subject of the Interpol alert.
The British authorities knew that Lewthwaite was of potential interest to the security services at the time when her new UK passport was issued in February 2011, a government source said. Whether she used the new British passport to travel in 2011 is not known. A Home Office spokesman said: "We do not routinely comment on individuals, nor on security matters."