The widow of one of the July 7 bombers, who spent part of her childhood in County Down, and is known to be in East Africa has gained “semi-mythical status” since travelling to the region, a terror expert said.
Raffaello Pantucci, a senior research fellow at the Royal United Services Institute, said Samantha Lewthwaite had been “elevated” in perception since going there.
There have been conflicting witness accounts about whether a white woman was among the attackers in Nairobi, fuelling speculation over whether Lewthwaite, who was married to July 7 bomber Jermaine Lindsay, was involved.
Mr Pantucci said: “There has been a lot of speculation about it. Samantha Lewthwaite, since she appeared in East Africa, has been elevated in some ways to a semi-mythical status.
“I don’t think we’ve had any concrete evidence of her being involved in this incident, but the fact of her being mentioned in this context is not surprising because of her connections, and it is known that she is somewhere in East Africa.”
Lewthwaite is already wanted by Kenyan police over alleged links to a terrorist cell that planned bomb attacks on the country’s coast.
In March last year officials said that she had fled to Somalia, and that police were hunting a woman who used several identities, including hers.
Her mass killer husband, Lindsay, 19, carried out the most deadly of the July 7 attacks, claiming 26 lives.
Mr Pantucci said he believes UK intelligence services will view the violence in Kenya as a regional terrorist atrocity, with no significant effect on the terror threat to Britain.
Somali-based militant group al-Shabab has claimed responsibility for the atrocity.
Witness accounts have suggested a woman was among the attackers, fuelling speculation that wanted Samantha Lewthwaite, nicknamed the “White Widow, was involved.
In March 2012 it was reported that Lewthwaite, 29, who is originally from Aylesbury, Buckinghamshire and spent time in Banbridge, had fled across the border from Kenya to Somalia.
David Cameron is returning to Downing Street to oversee the response to attack.
The Prime Minister, who has warned the country to be braced for “more bad news”, is cutting short a Balmoral visit to chair a Cobra emergency committee meeting this afternoon.
Gunfire has reportedly been heard from inside the Westgate Mall this morning, where Kenyan Defence Forces are still involved in a hostage rescue operation.
Earlier the authorities said “most of the hostages” had already been rescued and the majority of the building had been secured in a major military operation.
The UK has offered Kenya assistance, including intelligence co-operation, in response to the attack by Islamic extremists in the upmarket shopping centre which has left 68 dead and more than 170 injured, including many children.
One of the Britons killed in the attack has been named in reports as Ross Langdon, who had dual nationality with Australia.
The architect is believed to have died alongside his girlfriend who was heavily pregnant.
Somali-based militant group al-Shabaab claimed responsibility for the atrocity, which Mr Cameron described as an “absolutely sickening and despicable act of appalling brutality”.
The Foreign Office is investigating suggestions that Ms Lewthwaite could have been involved.
A Foreign Office spokesman said: “We are aware of the reports and we are looking into them.”
The spokesman added: “It is really difficult to substantiate. We are looking at the names and seeing what we can find out.”