Boris Johnson has come under fire for putting personal ambition ahead of the country by backing a vote to leave the European Union.

And his fellow Conservative Eurosceptic Iain Duncan Smith has also received criticism after saying that continued membership of the EU puts the UK at greater risk of Paris-style terrorist attacks.

After days of speculation, Mayor of London Johnson finally revealed he would be backing the Leave campaign this evening, saying that he wanted the UK to “take back control” of its ability to govern itself. The news comes as a blow to David Cameron, as the latest tally of Tory MPs show more now want to leave the EU than back their own leader’s renegotiation.

However, Johnson has been accused of making the announcement in order to give him the edge in the race to become the next Tory leader.

Shadow Europe minister Pat Glass said that the move revealed “more about the Tory leadership contest and Boris’ own positioning than what is in the best interests of Britain.” She said that Labour would get on with the job of fighting to keep Britain in the EU while the Conservatives focus on their own internal politics.

“While the successors to David Cameron are positioning themselves, Labour will focus on what’s best for Britain – defending the jobs and rights protected by our EU membership,” Glass said.

Her remarks about Boris’ position were echoed by veteran Tory MP Nicholas Soames, who tweeted that Johnson “really isn’t an Outer”.

I am so sorry that the Boris is to campaign Out not least because he really isn't an Outer by conviction. Am sad to be opposing old friends — Nicholas Soames (@NSoames) February 21, 2016

Controversial Work and Pensions Secretary Iain Duncan Smith revealed that he would be supporting a Leave vote over the weekend, and shocked people today when he suggested that the EU’s immigration rules lead to incidents such as “what happened in Paris” – a reference to November’s terrorist attacks in the city.

He was condemned by Shadow Home Secretary Andy Burnham, who said the comments were “highly irresponsible” and “inaccurate to boot”. “It raises the question of whether ministers campaigning for Brexit can realistically remain within the Cabinet if the statements they are making are so fundamentally at odds with settled Government policy,” he said.

“As Iain Duncan Smith well knows, the UK opted out of the Schengen open borders agreement and therefore retains control over who comes in and out of the country, and even the Prime Minister and Home Secretary said yesterday that our membership of the EU brings real benefits in terms of security cooperation.

“The sharing of information helps us better protect our country and, as somebody who was in the Home Office on July 7th and 21st 2005, I saw first-hand how the European Arrest Warrant stopped terrorists evading justice.

“These misleading comments are not worthy of a senior Cabinet Minister and demean what needs to be a serious debate about our country’s future.”