MI6 boss warns that Britons returning from ISIS are 'very dangerous'

The head of MI6 has warned that ISIS fighters returning to Britain are 'potentially very dangerous' but cannot be stopped from entering the country. 

In rare public comments, Secret Intelligence Service chief Alex Younger said returning militants had acquired 'skills and connections' which would make them a threat. 

It comes amid a fierce debate over East London schoolgirl Shamima Begum, whose family have pleaded for Britain to let her return after she fled to join ISIS in 2015.  

Mr Younger's comments put him at odds with Home Secretary Sajid Javid who had indicated he would block her from re-entering Britain. 

Thousands of people have fled from ISIS as the terror group battles for its final patch of territory in Syria.  

Speaking in Munich, Mr Younger did not comment on Ms Begum's case specifically but warned the returning fighters were an 'extremely complex and difficult problem', the Evening Standard reported. 

'Public safety is the first thing that we will consider,' he said at the Munich Security Conference. 

'It follows from that that anyone who has put themselves in this situation can expect to be questioned and investigated and potentially prosecuted if they return to our jurisdiction. 

'We are very concerned about this because all experience tells us that once someone has put themselves in that sort of position they are likely to have acquired the skills and connections that make them potentially very dangerous.

'The reality is that so far, it has been a completely manageable problem.

'I can't predict accurately what will happen in future, but it's a very complex environment.'

British nationals had a right to return to the UK, he said.  

Sajid Javid had said he would 'not hesistate' to stop the return of people who left Britain to join ISIS who he said were 'full of hate for our country'.  

Mr Younger said ISIS, or Daesh, has morphed and is proving 'adept at inspiring at attacks rather than directing them', he said.

'Al Qaeda, which has always been in a rivalry, and almost zero sum relationship with Daesh, has, I think, undergone a certain resurgence as a result of the degradation of Daesh. It is definitely not down and out.'

Mr Younger also indicated that former spy Sergei Skripal could still be in danger from Russia, after he survived an assassination attempt in Salisbury lat year. 

Russia was 'intent on breaking up the links and alliances that exist' between Western states and that he was determined to attach a cost to any such efforts, he said.

Asked about Skripal, he said: 'I think there is a standing threat from the GRU (military intelligence agency) and other Russian intelligence services and that very little is off limits.' 

Yesterday, the father of one of the 'Bethnal Green three' said Britain has a duty to welcome Shamima Begum back. 

He told MailOnline: 'She should be allowed to come home and have her baby in peace'.

Abase Hussen, whose daughter Amira is thought to be alive and still alongside ISIS in Syria, said the schoolgirls are victims who should be 'helped, not punished'. 

Miss Begum is heavily pregnant with her third child and living in a Syrian refugee camp. She says Amira is alive but Kadiza Sultana, the third girl who fled the UK with them, died in an air strike two years ago.

Mr Hussen, 52, who once was filmed at a London flag-burning rally attended by Anjem Choudary, said the three young jihadi brides had 'just made a mistake'.

'These girls were young,' he told MailOnline. 'They were manipulated by evil people and they should be brought home and helped. Not punished. They pose no threat.

'The British government have not done anything to help me or the other parents. We have been badly treated. 

'Shamima should be allowed to come home and have her baby in peace. 

'I'm just waiting for the time when I can see my daughter. Ever since she left I have had hope. Tomorrow is another day. You never know what will happen tomorrow. The last time I spoke to her was a very, very long time ago.'