Britain is still at risk of crashing out of the EU without a Brexit deal or transition period if it does not produce a solution to the Irish border issue, the president of the European Council has warned.

Donald Tusk said Britain had “caused the problem” in Ireland by voting for Brexit and would therefore have to help solve it.

His comments, made in the European parliament, come on the first day of talks between negotiators on the future relationship between Britain and the UK – something the British side has wanted since last year.

“We want to use the positive momentum in these negotiations to finally settle outstanding issues such as the solution to avoid a hard border between Ireland and Northern Ireland,” Mr Tusk told MEPs in his report to MEPs on the March European Council summit.

“The UK’s decision on Brexit has caused the problem, and the UK will have to help solve it. Without a solution there will be no withdrawal agreement and no transition. Leaders will assess the negotiations in June. In parallel we will start our first talks about the future UK-EU relationship.”

In addition to discussions on the future relationship, senior officials will also discuss the Northern Ireland border issue. The most recent reports from sources close to the negotiations suggest there has been little progress on that issue since the March meeting of the Council.

The UK’s decision on Brexit has caused the problem, and the UK will have to help solve it Donald Tusk, European Council president

“Ireland is the outstanding issue. We’re all Irish in this regard. A clearly message to be passed on: we stand firmly behind our Irish friends,” said Manfred Weber, the leader of the centre-right European People’s Party and an ally of German chancellor Angela Merkel said.

Syed Kamall, the UK Conservative leader of the European parliament’s ECR group, welcomed the start of future relationship talks, telling MEPs: “Now we can stop talking about the past and focus on the future.”

But European Parliament Brexit coordinator Guy Verhoftsadt warned that “after the Windrush scandal in Britain we need to ensure the same is not happening to our European citizens” and that discussion of the withdrawal agreement and citizens’ rights was “not over”.

Brexit threatens life on the Irish border: in pictures Show all 15 1 /15 Brexit threatens life on the Irish border: in pictures Brexit threatens life on the Irish border: in pictures An abandoned shop is seen in Mullan, Co Monaghan. The building was home to four families who left during the Troubles. The town was largely abandoned after the hard border was put in place during the conflict. Mullan has seen some regeneration in recent years, but faces an uncertain future with Brexit on the horizon Reuters Brexit threatens life on the Irish border: in pictures A defaced ‘Welcome to Northern Ireland’ sign stands on the border in Middletown, Co Armagh Reuters Brexit threatens life on the Irish border: in pictures Mervyn Johnson owns a garage in the border town of Pettigo, which straddles the counties of Donegal and Fermanagh. ‘I’ve been here since 1956, it was a bit of a problem for a few years. My premises has been blown up about six or seven times, we just kept building and starting again,’ Johnson said laughing. ‘We just got used to it [the hard border] really but now that it’s gone, we wouldn't like it back again’ Reuters Brexit threatens life on the Irish border: in pictures Farmer Gordon Crockett’s Coshquin farm straddles both Derry/Londonderry in the North and Donegal in the Republic. ‘At the minute there is no real problem, you can cross the border as free as you want. We could cross it six or eight times a day,’ said Crockett. ‘If there was any sort of obstruction it would slow down our work every day’ Reuters Brexit threatens life on the Irish border: in pictures John Murphy flies the European flag outside his home near the border village of Forkhill, Co Armagh Reuters Brexit threatens life on the Irish border: in pictures Potter Brenda McGinn stands outside her Mullan, Co Monaghan, studio – the former Jas Boylan shoe factory which was the main employer in the area until it shut down due to the Troubles. ‘When I came back, this would have been somewhere you would have driven through and have been quite sad. It was a decrepit looking village,’ said McGinn, whose Busy Bee Ceramics is one of a handful of enterprises restoring life to the community. ‘Now this is a revitalised, old hidden village’ Reuters Brexit threatens life on the Irish border: in pictures Union Flag colours painted on kerbstones and bus-stops along the border village of Newbuildings, Co Derry/Londonderry Reuters Brexit threatens life on the Irish border: in pictures Grass reflected in Lattone Lough, which is split by the border between Cavan and Fermanagh, seen from near Ballinacor, Northern Ireland Reuters Brexit threatens life on the Irish border: in pictures Donegalman David McClintock sits in the Border Cafe in the village of Muff, which straddles Donegal and Derry/Londonderry Reuters Brexit threatens life on the Irish border: in pictures An old Irish phone box stands alongside a bus stop in the border town of Glaslough, Co Monaghan Reuters Brexit threatens life on the Irish border: in pictures Billboards are viewed from inside a disused customs hut in Carrickcarnon, Co Down, on the border with Co Louth in the Republic Reuters Brexit threatens life on the Irish border: in pictures Seamus McQuaid takes packages that locals on the Irish side of the border have delivered to his business, McQuaid Auto-Parts, to save money on postal fees, near the Co Fermanagh village of Newtownbutler. ‘I live in the south but the business is in the North,’ said McQaid. "I wholesale into the Republic of Ireland so if there’s duty, I’ll have to set up a company 200 yards up the road to sell to my customers. I’ll have to bring the same product in through Dublin instead of Belfast’ Reuters Brexit threatens life on the Irish border: in pictures A disused Great Northern Railway line and station that was for customs and excise on the border town of Glenfarne, Co Leitrim Reuters Brexit threatens life on the Irish border: in pictures Alice Mullen, from Monaghan in the Republic of Ireland, does her shopping at a former customs post on the border in Middletown, Co Armagh. ‘I’d be very worried if it was a hard border, I remember when people were divided. I would be very afraid of the threat to the peace process, it was a dreadful time to live through. Even to go to mass on a Sunday, you’d have to go through checkpoints. It is terribly stressful,’ said Mullen. ‘All those barricades and boundaries were pulled down. I see it as a huge big exercise of trust and I do believe everyone breathed a sigh of relief’ Reuters Brexit threatens life on the Irish border: in pictures A bus stop and red post box stand in the border town of Jonesborough, Co Armagh Reuters

The provisional agreement reached in December suggested that Britain would either produce a "specific" solution to solve the border issue, negotiate a trade settlement with the EU that meant one was not required, or use a "backstop" agreement that kept UK rules in full alignment with the EU where necessary.

The EU says Theresa May's decision to leave the customs union and single market rules out the trade agreement route, so Brussels negotiators have said they are waiting for Britain to come up with a specific solution. Senior UK government officials have however said they are still focusing on the trade agreement route.