Boris Johnson said he would need help from the European Union to avoid crippling trade tariffs or a hard border with the Republic of Ireland in the event of a no-deal Brexit, should he win the race to become the next leader of the Conservative Party and Britain's new prime minister.

In a BBC interview, he said the matter would be " not just up to us" but also stressed that he did "not believe for a moment" that a no-deal Brexit was a likely scenario, despite having already publicly said he would be willing to lead one, and then later reinforcing this position by saying the scheduled leave date of Oct 31 was a "do or die" date.

The status of the frontier between Northern Ireland, part of the United Kingdom, and the Republic, an EU member state, has been one of the most insurmountable obstacles in the Brexit process so far.

Currently there is no hard border between the two, but a no-deal Brexit could see one re-introduced, which could prove devastating economically and socially.

Frontiers, barriers and checkpoints would be a visual reminder of and potential trigger for the restart of the civil conflict in Northern Ireland known as the Troubles, which resulted in more than 3,000 deaths from the late 1960s into the 1990s.

Despite numerous statements from the EU that the issue is not open for more discussion, Johnson insisted he would be able to persuade Brussels to help solve it.

He said the issue of border checks could be avoided by "abundant technical fixes" but when challenged on whether they existed, he said: "Well, they do actually, you have in very large measure they do, you have trusted trader schemes, all sorts of schemes that you could put into place." However, he added that there was "no single magic bullet" to solve the problem.

The BBC interview took place shortly after Sky News postponed a planned televised head to head debate with leadership rival Jeremy Hunt, because Johnson would not confirm his attendance.

Work and Pensions Secretary Amber Rudd has urged Johnson to reconsider his reluctance to get involved in televised debates－having also done so earlier in the campaign－calling it "very odd".

When asked by the BBC about a row he had with his partner Carrie Symonds on Friday night, which led to the police being called, Johnson refused to be drawn saying it was "simply unfair" to involve "loved ones" in a political discussion.

However, Monday morning's newspaper front pages featured pictures of Johnson and Symonds, supposedly taken at the weekend, suggesting the couple were on good terms, until it was pointed out that in the photos, his hair is clearly a different length.

In another interview on the LBC radio station on Tuesday morning, Johnson was asked 26 times about the origins and source of the photos, and again refused to answer.

In the same discussion, he also said reports he had been taking advice from right-wing US political strategist Steve Bannon were "codswallop", despite Bannon having been filmed talking about their discussions "back and forth" about a key speech made by Johnson.