London Mayor Boris Johnson has continued his pro-Brexit campaigning in Westminster, opining that the UK's EU membership only hinders Britain's ability to tackle terrorism.

Giving evidence before the House of Commons Treasury Committee, the Tory politician evoked this week's shocking attacks on Brussels and said:

"We are thinking today particularly about how to combat terrorism and the threat that that poses to our societies. I've seen various people quoted as saying that remaining in the EU is essential for security.

"I think it's important to put a countervailing point which is that there are some ways now that the European Court of Justice is militating against our ability to control our borders in the way we want to and indeed to maintain proper surveillance".

Johnson also argued that support for the EU in his city was "shallow" and that a Brexit would not effect London's standing in the financial world.

He conceded that he was "generally aware" of surveys showing that the City of London is in favour of remaining within the EU, but said that that support is fragile indeed.

Citing the banking likes of Lloyds chairman Lord Blackwell and RBS non-executive director Lady Noakes as City figures backing a Brexit, Boris told the committee:

"I’m struck by how shallow the enthusiasm for the EU seems to be amongst its supposed backers.

"It’s interesting that when you dig into these people’s opinions, they are much less strongly held than you might suppose...

"What has struck me in private conversations which I occasionally have with leading bankers about this is how finely balanced they see it to be.

"Most of them will candidly say they don’t believe it will do any damage to London’s position as the world’s leading financial centre. That is the overwhelming picture I get".