British PM told his Brexit plans must include an Irish border referendum

British Prime Minister Boris Johnson has been told his preparations for a no-deal Brexit must include planning for an Irish border referendum, a day after his demands for the backstop to be scrapped were met with a fl at refusal from the Irish prime minister, Leo Varadkar.

Johnson's first visit to Northern Ireland as prime minister this week comes as the United Kingdom faces deadlock in Brexit talks with the European Union, and with Northern Irish parties deadlocked in trying to restore a devolved government at Stormont, the legislature for the region.

After talks in Belfast on Wednesday, Sinn Fein leader Mary Lou McDonald revealed her party had challenged Johnson "very strongly" on his promise to take the UK out of the EU on Oct 31, with or without a divorce deal, and repeated her demand for a public poll on Irish unification in the event of a hard exit.

The issue of how to manage the land border on the island of Ireland after Brexit has caused deep divisions, not only in Westminster but between London and Brussels too.

"We've set out very clearly that this will be catastrophic for the Irish economy, for Irish livelihoods, for our society, for our politics and f or our peace accord," McDonald said.

"We've made it clear to him that the extensive planning that he tells us he's carrying out in respect of a potential crash Brexit has to include the constitutional question and the issue of a border poll here in Ireland."

In comments before the visit to Belfast, Johnson stressed that devolution needed to be restored as matter of urgency.

"The people of Northern Ireland have now been without an executive and assembly for two years and six months－put simply this is much, much too long," he said.

Earlier in the week, Johnson and Varadkar clashed in their first exchange of views on Brexit since the former mayor of London became prime minister.

Johnson told Varadkar the UK would never put physical checks or infrastructure at the border with Northern Ireland after Brexit but demanded the backstop－the mechanism to avoid an Irish hard border－be scrapped.

Varadkar reiterated that the backstop was needed because of decisions made by the UK, and that the EU was united in the view that it cannot be scrapped.

Johnson had been accused of snubbing his Irish counterpart by leaving it so long to speak to him, even though Varadkar will be central to whether he can agree a new withdrawal deal with the EU.

A spokesman for Varadkar said: "The taoiseach emphasised to the prime minister that the backstop was necessary as a consequence of decisions taken in the UK and by the UK government.

"Noting that the Brexit negotiations take place between the UK and the EU, the taoiseach explained that the EU was united in its view that the withdrawal agreement could not be reopened.

"Alternative arrangements could replace the backstop in the future, as envisaged in the withdrawal agreement and the political declaration on the future relationship, but thus far satisfactory options have yet to be identified and demonstrated."