A photo of Samantha Lewthwaite taken from her fake South African passport released by Kenyan police

The wife of one of the 2005 London bombings prime suspects, dubbed the "white widow", was today linked to the ongoing siege at a shopping centre in Kenya.Samantha Lewthwaite, the widow of bomber Jermaine Lindsay, was reportedly spotted shouting orders to gunmen in Arabic during the attack on the Westgate complex in the Kenyan capital, according to a media report.The 29-year-old is reportedly a member of Somali al-Shabab movement, which has claimed responsibility for the attack, and is wanted by Kenyan police over links to a suspected terrorist cell.According to the 'Daily Mirror', she is a British soldier's daughter from Aylesbury and a convert to Islam who was married to Lindsay when he carried out the London suicide bombings on the city's transport network in 2005.Meanwhile, the UK Foreign Office has confirmed that four British nationals have been confirmed as among those killed in the siege.Defence secretary Philip Hammond said next of kin had been informed and that the UK "stands ready" to provide more assistance to Kenya.At least 62 people have been killed since the attack began on Saturday.British Prime Minister David Cameron cut short a visit to Balmoral in Scotland to chair an emergency meeting in London this afternoon.Hammond chaired a meeting of Cobra, the government's emergency response committee, this morning.This was the third meeting of the group about the attack on the Westgate shopping centre in Nairobi.Around 10 attackers and some 30 hostages are still thought to be holed up inside as Kenyan security forces, including commando teams and military helicopters, launched a "final assault".Heavy gunfire and explosions have been heard on Monday, and smoke is now billowing out of the top of the building.In addition to the death toll, at least 170 people have also been injured.The Somali al-Shabab movement has claimed responsibility for the attack.

The UK Foreign Office said it expects the number of British fatalities to rise.