The onus on finding a workable solution to the Irish border problem post-Brexit remains firmly with the UK Government, a key European Parliament figure has insisted.

The parliament’s Brexit co-ordinator Guy Verhofstadt again suggested Northern Ireland remaining in the customs union and single market post-Brexit could provide a resolution.

That might be the way to avoid a hardening of the border.

But the Belgian MEP stressed it was for the UK Government to come up with the solution, insisting the ideas from Whitehall to date were not acceptable.

He is in Belfast on a two-day fact-finding mission to Ireland.

He told the Press Association a “unique solution” was needed to avoid a hard border.

“A unique solution in that there is no resurrection of a hard border in Northern Ireland because that is not in the interests of business in Northern Ireland and Ireland, neither in the interests of the citizens,” he said.

“That is also the reason I am here - to hear from the political parties in Northern Ireland how they can find this solution even though we all know this unique solution has to be proposed by the UK side, because the problem is a consequence of the decision of the UK to leave the European Union.”

Mr Verhofstadt will meet Northern Ireland’s political leaders later on Wednesday before visiting communities on the Irish border that harbour concerns about the impact of the UK’s exit from Europe.

The former Belgian prime minister will then travel to Dublin, where he will meet Taoiseach Leo Varadkar on Thursday and also address a special joint sitting of a number of Irish parliamentary committees.

Mr Verhofstadt, who is the link man between the EU negotiating team and the European Parliament, voiced scepticism about the UK’s position paper on the border post-Brexit, a document that suggested there would be no need for physical customs checks on the frontier even if the UK was outside the customs union.

“For the moment we don’t see a workable solution being put forward by the UK Government,” he said.

In an interview with RTE Radio One, he added: “There are possibilities, for example you could imagine one proposal on the table that Northern Ireland continued to be part of the customs union and even of the single market.

“The point is it is the UK Government that has to come forward with such unique solutions.”

The MEP’s visit comes ahead of next month’s crucial summit in Brussels when leaders of the EU 27 will decide whether sufficient progress has been made in the first phase of negotiations to progress talks to focus on future trading relations.

The EU has insisted progress has to be made in three key areas: citizens’ rights, the size of the UK’s exit bill and the shape of the Irish border post-Brexit.

Asked about speculation Prime Minister Theresa May will outline a sum the UK is prepared to pay in a keynote speech on Friday, Mr Verhofstadt said: “Let’s have the speech of Mrs May and then we can make an analysis.”

He said there remained a “dispute” on the exit bill and that there were “big differences” in terms of both sides’ position on citizens’ rights.

The parliament’s Brexit co-ordinator is starting his day in Belfast with a private tour of the city with academics from Queen’s University who specialise in history and politics.

He will then travel to Parliament Buildings, Stormont, where he will be greeted by the speaker of the crisis-hit assembly Robin Newton before holding meetings with political leaders.

Democratic Unionist leader Arlene Foster and Sinn Fein’s Stormont leader Michelle O’Neill will hold individual meetings with Mr Verhofstadt, as will Ulster Unionist leader Robin Swann, SDLP leader Colum Eastwood and Alliance deputy leader Stephen Farry.

After leaving Belfast, he will visit a farm that straddles the Irish border.

Mr Verhofstadt will then meet campaigners opposed to a hard Brexit and representatives from the road hauliers industry.

He will hold talks with Mr Varadkar on Thursday morning before addressing a joint sitting of a number of Dail committees.

ends After a meeting between Mr Verhofstadt and Sinn Fein politicians at Stormont, the party’s northern leader Michelle O’Neill said they had found him to be very understanding.

She said: “He’s very clear in dismissing the papers which the British government have produced to date and so I did find him a very understanding man and we need to take these opportunities to engage with him.

“I believe he’s someone who has been very aware of the implications of Brexit on the island of Ireland and someone who has been very strong in setting out his position on issues which need to be resolved before moving on to the next stage of negotiations.

“We’ve made very clear to him today the issues which we need to see - we need to remain in the customs union, we need to have access to the single market, we need to see no return to hard borders and to see citizens have access to the European Courts of Justice.”

Ms O’Neill added: “At least he’s had the manners to come and talk to people about the implications which is far more than any British minister has done.”

Mr Verhofstadt is due to meet representatives of all of Northern Ireland’s main parties at Stormont on Wednesday.

He will then travel to border areas in Armagh and Monaghan to discuss the future of the areas following the UK’s withdrawal from the EU.