DUP leader Arlene Foster has warned it would be "catastrophic" to create a barrier between Britain and Northern Ireland.

Ms Foster will meet the European Union's chief Brexit negotiator Michel Barnier on Tuesday to set out her red line on the issue, warning against any attempt to "annex" Northern Ireland.

The UK government has promised to set out further proposals on the backstop arrangement aimed at avoiding a hard border, with speculation that it could involve regulatory checks on goods travelling between Britain and Northern Ireland.

The DUP's ten MPs play a critical role in propping up British Prime Minister Theresa May's minority government at Westminster, and Ms Foster said her party's only red line was the prevention of a new border being created in the Irish Sea.

"We want the June 2016 referendum result to be respected and implemented," she said.

She added: "A majority of people throughout the United Kingdom voted to take back control of their money, laws and borders.

"Whilst many in Brussels may not agree with the referendum outcome, the result must be respected."

The EU's proposed backstop would see Northern Ireland effectively remain in the customs union and single market while the rest of the UK shifts away from Brussels' rules, something Mrs May has already said would be unacceptable.

Ms Foster said: "As we leave the EU, we should do so as one nation.

"The United Kingdom single market must be protected with no new borders between Northern Ireland and Britain being created. From day one this has been the DUP's only red line.

"This red line is recognising that Britain is Northern Ireland's biggest market.

"Over 70% of all goods leaving Belfast port are destined for Britain. To create a barrier to that trade would be catastrophic."

Northern Ireland must retain "unfettered access" to the British market and also be able to fully benefit from any new trade deals struck by the UK after Brexit, she said.

"Our red line also respects and protects Northern Ireland's constitutional place in the United Kingdom," she added.

"Many who claim to respect the Belfast Agreement fail to respect the principle of consent which was part of that agreement. Indeed, they would happily redraw the border and annex Northern Ireland away from the rest of the UK."

She called for a "sensible" Brexit which works for both the UK and the Republic of Ireland.