Boris Johnson: No military option for tackling IS should be ruled out

No military option for tackling Islamic State (IS) should be off the table, Boris Johson said as he warned a Paris-style attack on London could not be ruled out.

The London mayor said it was "unlikely" that an assault like that inflicted on Paris would occur in the British capital but it would be "impossible and irresponsible" to say it could not happen.

Mr Johnson suggested that the attacks could strengthen David Cameron's push for European Union reforms by making the case for better control at the borders.

Mr Johnson acknowledged there were concerns in the military about going to war against IS - also known as Daesh - in Syria, where the picture was complicated by the civil war against Bashar Assad's regime and the involvement of Vladimir Putin's Russia.

In his Daily Telegraph column, Mr Johnson said: