LONDON (Reuters) - The Northern Irish party which props up Prime Minister Theresa May’s government said on Friday that defending the province’s place in the United Kingdom was a priority that came ahead of delivering Brexit.

Democratic Unionist Party (DUP) deputy leader Nigel Dodds, speaks to the media outside the Cabinet Office, in London, Britain March 15, 2019. REUTERS/Henry Nicholls

The Democratic Unionist Party’s (DUP) 10 lawmakers voted against May’s deal on Friday, sounding its probable death knell and leaving the United Kingdom’s withdrawal from the European Union in turmoil on the day it was supposed to quit the bloc.

For the DUP, maintaining the union of Great Britain and Northern Ireland has always been its core belief, though it also supports Brexit.

It has repeatedly warned May against allowing any divergence, or possible divergence, between Northern Ireland and the rest of the United Kingdom after Brexit.

“I would stay in the European Union and remain rather than risk Northern Ireland’s position, that’s how strongly I feel about the Union,” the DUP’s deputy leader, Nigel Dodds, told the BBC. “The answer must be something that works for the whole of the United Kingdom - that’s our first and main priority.”

“We want to see Brexit delivered, we believe the referendum result should be respected and delivered on, but it can’t be at the risk of separating Northern Ireland out from the rest of the United Kingdom,” Dodds said.

The DUP was founded in 1971 at the start of Northern Ireland’s three-decades-long “Troubles”. More than 3,600 people died in fighting between Irish nationalists seeking a united Ireland, the British army and loyalists seeking to maintain the province’s status as British.

The DUP’s main issue with May’s deal has been the backstop - the troublesome insurance mechanism aimed at keeping Northern Ireland’s border with EU-member Ireland open after Brexit.

“We have said that were the backstop to become operational, Northern Ireland would sit in a separate legal position from the rest of the United Kingdom in economic and trade terms,” Dodds said in a statement.

“In those circumstances there is the strong possibility that we could have a long-term outcome whereby Northern Ireland would inevitably pull away from its biggest trading market in Great Britain as there would be new internal barriers within the United Kingdom.”

Dodds said talks with the British government had not made sufficient progress on how domestic legislation would ensure the economic integrity of the United Kingdom.

He urged May’s government to “return to Brussels on these issues and not simply to accept the position of the European Union as being unalterable.”

“Northern Ireland cannot be subjected to new and onerous trade barriers within the United Kingdom as the price of leaving the European Union,” Dodds said. “We deeply regret the numerous missed opportunities by those who negotiated on behalf of the UK.”

The European Union has made clear it will not reopen the divorce deal in which the backstop is enshrined.