The Democratic Unionist Party and its leader, Arlene Foster, have expressed considerable irritation that Northern Irish business leaders have backed the draft EU-UK Brexit agreement.

Ms Foster has privately warned that business people were in danger of being exploited for political reasons amid the current turmoil over Brexit, it is understood.

She was particularly annoyed by Thursday’s meeting in Belfast when Northern Ireland Secretary Karen Bradley spoke to the Northern Ireland Chamber of Commerce and Industry about the deal.

Ms Bradley hurriedly flew to Belfast to brief the 20-strong group, including executives from some of the North’s biggest companies, including Asda, Diageo, BT, SSE Airtricity, Dale Farm and Danske Bank.

A succession of business people from industry, food, farming and other sectors have come out arguing that the Brexit deal negotiated by UK prime minister Theresa May “is better than no deal”.

Ms Foster privately told chamber members she was unhappy with the attitude taken by business, and that they did not understand the threat the agreement posed to the union of Great Britain and Northern Ireland.

Equally, it is understood that the former First Minister also argued that the deal had no chance of gaining approval at Westminster.

Her view was reinforced by Lagan Valley DUP MP Jeffrey Donaldson, who on Thursday night claimed business people had “not read” the 585-page document.

Providing certainty The chamber’s vice-president, John Healy, said it was broadly supportive of the deal: “It is NI Chamber’s opinion that any deal is better than no deal for business,” said Mr Healy, who leads insurer Allstate Northern Ireland.

Despite the DUP’s annoyance, the chamber of commerce has held its ground, arguing the agreement on offer provides certainty and a reasonable way forward for business. The chamber would not comment on Friday.

Speaking later, Mark Ennis, non-executive chairman of SSE Electricity, said the backstop was an insurance policy no one wanted to have to use. For him, it guarantees the all-Ireland single electricity market.

“The worst thing for Northern Ireland would be a hard Brexit. It would lead to a lot of job losses, a lot of cost increases for normal families trying to live in Northern Ireland.”

Brian McConville owns MJM Marine, which employs 600 people, mostly in Co Down, refurbishing cruise liners, ferries, yachts and all kinds of public buildings throughout the world.

The options are clear, he says: this deal, no deal or a second referendum. For him there is no choice: “We don’t like the option of no deal, so I am nodding with the opinion that this is the best deal for us.”

He was impressed by Mrs May after a meeting with her. “She is working very sincerely, trying to get the best of everything for us all, both the mainland UK and Northern Ireland. Do I like the person? I think she is a great woman. I most certainly would not do her job, and I don’t think many would like her job,” Mr McConville said.

Donaldson says no DUP MP Jeffrey Donaldson went on BBC Northern Ireland’s, The View programme on Thursday night to tell presenter Mark Carruthers that those supporting the deal were “wrong”.

“I don’t believe they have read the detail of this. They have not read the 500 pages. There are serious constitutional and economic implications of this deal for Northern Ireland,” he said.

However, Mr Donaldson was quickly challenged by Ian Marshall, a former Ulster Farmers’ Union president and now a unionist member of the Seanad. Mr Donaldson was being “disrespectful”, he countered.

“There are still some areas where we would like clarification. Overall, the document now on the table would secure Northern Ireland’s existing agricultural trading relationships. That has always been our aim,” he said.

The 70-strong Ulster Farmers’ Union executive, representing 11,500 farmers, has met and agreed to reject a no-deal outcome . On Thursday the 10-strong board backed this position, with just one opposed.

Brexiteers such as Jacob Rees-Mogg appear to want to open up the UK to food imports from the US and Brazil, where food standards are lower. “Our food is safe to eat. Why would anyone want to lower standards?” Mr Marshall said.

Food and drink companies backed the farmers. Michael Bell of the Northern Ireland Food and Drink Association put it simply: “A no-deal Brexit is a grizzly prospect for the agri-food business.”