Police and ministers failed to respond quickly enough to reports a Londoner has left Britain bound for Syria, an MP has claimed.
Labour's Barry Gardiner said he had tried to co-ordinate a response after the 22-year-old Wembley man left his home on Monday night, apparently bound for Syria via Paris and Turkey.
But he told the BBC Radio 4 Today programme the police had only taken the man's computer for examination, while a series of Government ministers had told him it would be "inappropriate" for them to intervene on what was a matter for the police and Interpol.
The Brent North MP said Britain had a "responsibility" to both protect its citizen and those he might harm with his actions abroad.
Mr Gardiner said: "The police had notification since 11pm on Monday that this young man had absconded and the family were seriously concerned he was on his way to Syria.
"They had taken all that time, 24 hours, to do little more than take his computer for further investigation - that's the sort of time we need a central location for MPs to act swiftly to get in touch with the global response centre and ensure our embassy in Turkey or wherever else is alerted to stop them as they come into the country.
"This young man had come in from Paris that morning, he was then coming into Turkey later that day. He could have been apprehended coming into the country, he was not.
"There was failure to join up the response."
Mr Gardiner said he had contacted the offices of Foreign Secretary Philip Hammond, Security Minister John Hayes, Counter Extremism Minister Lord Ahmad and Middle East Minister Tobias Ellwood.
He said: "I spoke to the Foreign Secretary's private office and asked them to instigate something. The private secretary there put me in touch with the global response centre who then contacted me about half an hour later.
"They again said it was a matter for Interpol liaison with our police."
Mr Gardiner added: "My concern at the moment is for the family and to ensure we try and get this man man safely to this country and to stop him crossing the border into Syria.
"(It is) very difficult and extremely difficult when Government departments don't appear to be joined up in response."