Miss Lewthwaite's father Andy told the Times he did not believe she would be involved in a terror plot after travelling with her three children. "I haven't spoken to her for a long time," he said. I don't know if she's in this country or where she is. The Mujahidin group al-Shabaab, which is currently engaged in a guerrilla war against Kenyan security forces in Somalia and has links to al-Qaeda, is believed to be behind the cell. Up to 40 Britons are fighting with al-Shabaab. "I can give no details, but suffice it to say that we believe she is not a small fish," a senior police source in Nairobi. She entered the country to meet with other terror suspects in Mombasa using a South African passport under the name of Natalie Faye Webb, aged 26. But the name belongs to an English woman unconnected with the plot. Miss Webb lives with her parents John and Wendy in Southend-on-Sea, Essex. Miss Webb was reported as having connections to South Africa, her mother's native country, but was said to have never visited Kenya. Her father told the Times she was a victim of identity theft. "We have been liaising with officers from the anti-terrorism unit at New Scotland Yard to find out how this has come about," he said. Police are also hunting for a woman called Habib Ghani, from Hounslow, West London, who left Britain several years ago to live in Africa. Miss Lewthwaite, 27, was seven months pregnant with their second child when her husband launched his 7/7 attacks, although it emerged at the inquests last year that Lindsay was cheating on her.