Members of an alleged terrorist cell planning Mumbai type suicide attacks on Christmas shoppers in London received their training in Pakistan,according to sources. 'The Telegraph' reports that the cell is described as al-Qaeda inspired because no specific information has emerged about the links they may have made with the terrorist group in Pakistan. Although it is understood that the arrested men had not been communicating with al-Qaeda commanders while in Britain,security sources said it was unlikely that they did not at least attempt to make contact with al-Qaeda while they were abroad,and may have received advice and training. Investigators believe that it is significant that although most of the cell is British with Bangladeshi origins,its members chose to travel to Pakistan. The cell is thought to be associated with the banned extremist groups al-Muhajiroun and Islam4UK in Britain,as well as being followers of the Yemen-based al-Qaeda preacher Anwar al-Awlaki. On Monday,twelve suspects- aged between 17 and 28- were held during early morning raids by unarmed officers in London,Cardiff,Stoke-on-Trent and Birmingham,after months of surveillance by MI5,as they prepared to launch terror attacks in the week before Christmas,according to sources. A warrant of further detention has been granted to interrogate the men,who are being held at police stations around the country,until Boxing Day,the paper said. The main operators of the cell are said to have been in Stoke and Cardiff,with significant activity in East London,and the gang is said to have been planning a spectacular attack on commercial sites such as banks and shops along with iconic sites in London,the paper added. The British Government and top army commanders have decided to put the countrys crack SAS helicopters on a state of high alert to crush any Christmas terror attack. Meanwhile,British Home Secretary Theresa May has urged the countrys citizens to be vigilant. The official terror threat level is "severe",meaning an attack is likely.