British spies are deliberately not interviewing British Islamic State suspects in Syria partly because of fears any contact could strengthen the detainees’ case for returning to the UK, The Sunday Telegraph has learned. 

The government is worried that any encounter between MI6 officers and British Isil suspects risks giving the detainees a legal foothold which they could exploit to come back to Britain, UK officials said. 

Britain’s intelligence agencies have also been dogged by years of lawsuits over their role in the treatment of suspected jihadists abroad, leading MI6 officers to maintain “a strategic distance” from UK detainees in Syria. 

The result is that high-profile British suspects including…