Boris Johnson suggests he could back UK EU exit

Rose, third from left, at the launch of the pro-Europe campaign yesterday. Picture: PA

Speaking on a visit to Osaka in Japan, Mr Johnson has become one of the first members of the Tory leadership to make it clear he could back a so-called Brexit with only Justice Secretary Michael Gove previously suggesting he would vote to leave.

The intervention from one of the three favourites to replace David Cameron as Tory leader came as the campaign was launched to keep the UK in the EU, headed by former Marks and Spencer’s boss Lord Rose.

While Mr Johnson insisted that “in an ideal world” he would want to stay in a reformed EU, he played down the risks of a so-called Brexit.

The senior Tory repeatedly refused to rule out spearheading the campaign for the UK to leave the EU but insisted he had “great faith” in David Cameron’s ability to negotiate better terms of membership.

He said: “I think I am exactly where the Prime Minister is and, I think, actually a huge number of the proportion of the British public. We want, in an ideal world, to stay in a reformed European Union but I think the price of getting out is lower than it’s ever been. It’s better for us to stay in, but to stay in a reformed EU. That’s where I am.”

Mr Johnson has so far been careful to support Mr Cameron’s position of waiting to see the outcome of the renegotiation but many Eurosceptics believe his private views are more hardline than the Prime Minister’s.

And Ukip leader Nigel Farage said he believed the mayor could be persuaded to lead the campaign for Britain to leave the EU.

He said: “You are mounting hypothesis upon hypothesis.”

Meanwhile the launch of the Britain Stronger in Europe campaign saw former police chief Sir Hugh Orde warn that Britain could be viewed as a safe haven by international criminals if the country voted to end its relationship with Brussels.

Former Association of Chief Police Officers president Sir Hugh predicted “villains” would come to the UK to escape justice if the country voted to leave, as it would mean pulling out of EU-wide agreements on extradition and sharing evidence.

Speaking at the launch event in east London, he said: “If I was a villain somewhere else in Europe and I was escaping justice, I would be coming here because it’s going to take a lot longer to get you back.”

Cross-border extradition arrangements would also have to be redrawn, causing huge delays in the justice process, he said.