Brexit: Irish border checks will have to return if Theresa May fails to strike deal, expert warns

'It’s not their choice to say whether they are going to enforce the border or not - they would be obliged to do so'

International law will force the return of checks at the Irish border if there is a no-deal Brexit, MPs have been told – despite Theresa May’s claim she would never take bring them back.

Both London and Dublin would have “no choice” but to impose a hard border if the UK crashes out of the EU without an agreement, an expert in cross-border law said.

Dr Katy Hayward, from the University of Belfast, also warned of “dangerous goods” being smuggled into the UK if the prime minister attempted to defy the law and keep the border open.

Both the UK and Irish governments have said they will not introduce border checks, even as the risk of a no-deal Brexit rises with the talks deadlocked.

It follows warnings, including from police chiefs, that they would “play into the hands” of terrorists, by becoming an easy target for dissident paramilitaries.

But, Dr Hayward told the all-party Brexit committee: “If the UK is saying it is not enforcing a border at this point, there is a risk of smuggling of dangerous goods into the UK through its open borders.”

And, asked if governments could allow that situation to continue for “years”, she replied: “It’s not their choice to say whether they are going to enforce the border or not - they would be obliged to do so under international law.

“On the Republic of Ireland side, from the whole of the EU there would be an expectation that a customs border would be enforced.”

Philip Hammond, the chancellor, has also privately suggested that World Trade Organisation (WTO) rules would force the UK to bring back checks without a deal.

And other EU countries are thought to have warned Dublin they would consider checks on trade from the Republic to the continent, if it failed to act.

Stephen Kelly, the chief executive of Manufacturing NI, said the notices simply told companies to contact the Irish government – telling the MPs the message was “have a word with the Irish, we'll come back to you”.

“The vast bulk of people are sitting with their heads in their hands looking for some clarity. The overwhelming reaction is one of worry, concern and waiting,” he said.

The stalemate in the Brexit talks is over the EU’s requirement for a “backstop”, to keep Northern Ireland aligned to EU customs and single market rules until a solution to avoid a hard Irish border can be found.

Ms May has called it “unacceptable” – and Tory MPs have branded it an “annexation” of UK territory – but Dr Hayward argued people in Northern Ireland preferred it to the damage from crashing out of the EU.

“A majority of business and civic leaders and political parties in Northern Ireland say a backstop is acceptable. If it’s between that and a no deal, a backstop is preferable.”

Aodhan Connolly, director of the Northern Ireland Retail Consortium, echoed that message, saying: “A backstop id not perfect, but is much, much preferable to the alternative of a no deal.

Warning beef prices would soar by 37 per cent, and cheese prices by 43 per cent, Mr Connelly added: “The Northern Ireland shopper does not have the ability to absorb these cost rises.”