Boris Johnson leaves door open for second Brexit vote

Boris Johnson has refused to rule out a second Brexit vote if next month's referendum sees a knife-edge victory for the Remain campaign.

The former London mayor insisted he expected the Leave side to score a "decisive" victory, but left the door open to pushing for a second poll if things did not go his way.

The remarks follow those of Ukip leader Nigel Farage which left Prime Minister David Cameron insisting he would not tolerate a "neverendum" repeat of the June 23 showdown.

The comments came in the wake of a blistering, highly personal, assault on Mr Johnson from Tory grandee Lord Heseltine, in which the former deputy prime minister warned he would be "very surprised" if the ex-London mayor would ever lead the party after his "obscene" remarks backing Brexit which compared the EU to Hitler.

Mr Johnson declined to rule out a second referendum in light of a tight result, insisting: "I think to start getting into all sorts of complicated, off-the-back-cushion calculations about further referendums is pointless. We are going to win."

The ex-mayor's spokesman insisted it was the "arguments that matter", not personal attacks.

In a bid to push immigration back to the top of the campaign agenda, the Leave side seized on a report by crime-fighting organisation Interpol and its European counterpart Europol, which warned that 800,000 migrants were waiting in Libya to try to make the crossing to Europe.

Ukip leader Mr Farage insisted that failure to control immigration could lead to blood on the streets of Britain.

He told the BBC: "I think it's legitimate to say that if people feel they have lost control completely - and we have lost control of our borders completely as members of the European Union - and if people feel that voting doesn't change anything, then violence is the next step.

"I find it difficult to contemplate it happening here - but nothing is impossible."

The Interpol/Europol report stated: "Overall, an increase in the number of migrants trying to reach the EU is expected. In Libya alone, around 800,000 migrants are waiting to travel to the EU."

The probe found that while a systematic link between people smuggling and terrorism had not been proven, there was "increased risk" terrorists might use migratory flows as cover.

"The systematic link between migrant smuggling and terrorism is not proven, there is an increased risk that foreign terrorist fighters may use migratory flows to (re)enter the EU," the report said.

Migrants are vulnerable to sexual exploitation in order to pay debts to smugglers, the study said, with people traffickers making between five and six billion dollars from their trade last year.

In a withering assessment of Mr Johnson's campaign performance, Lord Heseltine told the BBC: "He is behaving now irresponsibly and recklessly and I fear that his judgment is going."

Asked if he believed Mr Johnson would ever lead the Conservative Party, the peer said: "I'd be very surprised. I think every time he makes one of these extraordinary utterances, people in the Conservative Party will question whether he now has the judgment for that position."

Labour shadow chancellor John McDonnell said Tory in-fighting on Brexit was "turning into a pub brawl".