One of two teenagers feared to have crossed into Syria to join ISIS is believed to be a relative of Hammaad Munshi ( pictured ) , who became Britain 's youngest convicted terrorist when he was found guilty of terror offences at the age of 18 in 2008 . A relative of Britain 's youngest convicted terrorist is believed to be among two teenagers who have fled into Syria to join Isis . The pair from Dewsbury , West Yorkshire , have not been in contact with their families for several days and can not be reached on their mobile phones . One of the boys is believed to be a relation of Hammaad Munshi , who was just 15 when he joined a cell of Islamic fanatics targeting the Royal Family . The grandson of a British sharia judge , Munshi was recruited by a leading 'cyber terrorist ' who radicalised impressionable Muslims and encouraged them to attend military camps in Pakistan . He was arrested on his way home from a chemistry exam in 2006 and found with two bags of ball-bearings - key material for a suicide vest . He was locked up for two years under the Terrorism Act in 2008 . The Times reported that the two 17-year-old boys told relatives that they were going on a school trip , but instead used the Easter holidays as a 'window of opportunity ' to flee Britain . They are thought to have boarded a Thomas Cook flight from Manchester Airport to Dalaman in Turkey on March 31 , said West Yorkshire Police . Both families have reported the boys missing to police although British authorities now fear that the pair have managed to cross into Syria from Turkey . A family friend said they were in a state 'of total disbelief ' and they were 'broken and inconsolable ' . The south Dewsbury area has been linked to a number of extremist plots and was home to the ring-leader of the London bombings on July 7 , 2005 , Mohammad Sidique Khan . According to The Times , a member of one of the families said : 'We do n't want to talk . ' Assistant Chief Constable Mark Milsom , from West Yorkshire Police said : 'We are extremely concerned for the safety of these two boys and would urge anyone with information to come forward and speak to us . 'Syria is an extremely dangerous place and the public will be aware of the dangers these boys may face . 'The choice of returning home from Syria is often taken away from those that come under the control of Islamic State , leaving their families in the UK devastated and with very few options to secure their safe return . ' The force said it has been supporting the missing teenagers ’ families and carrying out extensive inquiries alongside the North East Counter Terrorism Unit . The disappearance of the two teenagers follows the arrest of nine Britons by Turkish authorities attempting to sneak into Syria across the Turkish border . Waheed Ahmed , 21 , from Rochdale was arrested with his aunt , cousins and four children while attempting to get into Syria . Scroll down for video . 'Seeking jihad ' : Two teenage boys from Dewsbury , West Yorkshire , are believed to have fled to Syria to join Isis militants , seen here taking control of the Yarmouk refugee camp in Damascus . After the arrest , anti-terror police raided the home of his father , Shakil Ahmed , a respected Labour councillor for the town . Munshi 's family comes from Dewsbury in West Yorkshire , where his grandfather Yakub Munshi ran the town 's sharia court . The schoolboy , who was studying for his GCSEs at Westborough High School in Kirklees , West Yorkshire , was traced through his online conversations with 'cyber terrorist ' Aabid Hussain Khan . In one MSN chat , they argued how best to sneak a metal sword through airport security . Munshi had painstakingly scoured the internet for details on how to make napalm and grenades . He claimed he had only done the research out of curiosity but handwritten notes hidden under his bed revealed his burning desire to travel abroad to become a martyr . The boys are from the same town as London 7/7 suicide bomber Mohammed Siddique Khan ( pictured ) Munshi also had a library of videos , documents and audio clips showing acts of jihad , mujaheddin fighters and Al Qaeda preachings . He was arrested as he walked home from school after an exam . Khan , who acted as an administrator on an extremist website called Activion Publications , downloaded information on the Queen , the Duke of Edinburgh , Prince Charles and Camilla , Prince Edward , the Countess of Wessex , The Duke of York and the Princess Royal . Munshi was convicted of making a record of information likely to be useful in terrorism . Khan was found guilty of possessing articles for a purpose connected with terrorism but cleared of a similar charge . A third man , Sultan Muhammad from Manningham , West Yorkshire - Khan 's cousin - was convicted of three similar charges and one of making a record of information likely to be useful in terrorism .
Two 17-year - olds have not been in contact with relatives for several days . ' amongst relatives they were taken on a school trip during Easter holidays ' One is ' relative of Hammaad Munshi , who attended Islamic school aged just sixteen '