The SIS has moved to clarify its actions after it emerged the state spy agency had intervened to stop people who were threatening to fight with the Islamic State in Iraq and Syria.

Earlier this week, the Prime Minister revealed families had been in touch with authorities to raise concerns about relatives who may have been radicalised.

He mentioned that people had been 'talked down' following intervention by security services.

A spokesman for the intelligence agency confirmed staff have spoken to people about the situation in the Middle East and given them factual information.

However the SIS says staff know they can't issue warnings following a recent directive from the Inspector General of Intelligence and Security.

The issue of warnings, and their power to give them, remains under review.