Downing Street has dismissed a call by Boris Johnson for the government to introduce a "rebuttable presumption" that anyone who visits a war zone without providing notice will be guilty of a terrorist offence.
The prime minister's spokeswoman said David Cameron had no interest in"kneejerk" responses to the threat posed by Islamic State (Isis) fighters. She confirmed that Britain's intelligence agencies had not been pressing for the London mayor's idea.
The language used by No 10 was designed to contrast with the proposal by Johnson in his Daily Telegraph column on Monday for a change in the law which would effectively end the presumption of innocence for anyone who travelled to war zones without providing notice. The London mayor wrote: "The law needs a swift and minor change so that there is a 'rebuttable presumption' that all those visiting war areas without notifying the authorities have done so for a terrorist purpose."
Downing Street said the authorities would investigate people who travelled to Syria and Iraq, though this was a difficult task because many fighters do not travel via Europe.
Asked whether the prime minister would be amending legislation, the No 10 spokeswoman said: "The discussions on the level of response are ongoing. Things will need to be looked at. We are very clear that this is a generational struggle that we face where part of this whole challenge will be tackling the ideology too. It is not one about kneejerk response [with] specific proposals. It is about approaching these things – patient and resolute."
The spokeswoman confirmed that neither the security services nor the police had been pressing for the change in the law proposed by Johnson. She said: "It is not an idea I am aware the agencies have been pushing."
But the spokeswoman confirmed, as the home secretary Theresa May wrote over the weekend, that the government was looking at plans to make it easier to proscribe organisations that support extremism.
The No 10 spokeswoman added that the government already had a range of powers to deal with British jihadi fighters, ranging from revoking passports and stripping citizens with dual nationality and even naturalised citizens of their citizenship. The spokeswoman said: "People who insist on travelling to Syria and Iraq will be investigated by the police and the security services. For those who have dual nationality the home secretary already has the power to strip them of their citizenship and exclude them from the country. In certain circumstances the home secretary can now remove citizenship from naturalised Britons. We are also working with other European countries to disrupt and prevent travel to the region. But we need to be clear on what are the measures we are able to do and what do the police and the security and intelligence agencies – what are the measures they want in order to be able to tackle that? That should be driving the discussion."
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