NEW YORK - Prime Minister Theresa May said on Tuesday it would not be in Britain's national interest to hold another general election just as she is negotiating the terms of Britain's exit from the European Union.

May is subject to intense criticism at home and in Brussels over her approach to leaving the EU, fuelling speculation that she could be ousted by her own party, or that her minority Conservative government could collapse.

"What I'm doing is working to deliver a good (Brexit) deal with Europe in the national interest. It would not be in the national interest to have an election," May told reporters on board her official plane en route to New York, where she will attend the United Nations General Assembly.

May's Conservatives and the main opposition Labour party are running largely neck and neck in opinion polls.

She said Britain would reach a deal despite a current impasse in talks with Brussels and ruled out a second Brexit referendum. Britons voted by a 52-48 percent margin in a 2016 referendum to leave the EU.

Asked if she was "bluffing" when she said no deal is better than a bad deal with the EU, May told the BBC: "No. What we issued yesterday was some more technical notices to help businesses and others who would need to prepare in a 'no deal' situation for doing that. That's the right, sensible approach."

PRO-BUSINESS BREXIT

Addressing business leaders on Wednesday, May will pledge that her government will be "unequivocally pro-business" as it seeks to forge a future role outside the EU.

The perceived likelihood that Britain leaves the EU without a deal in just over six months is increasing because May has yet to reach a full divorce agreement with Brussels.

May will say she has no plans to abandon her current Brexit plan, shrugging off criticism at home and in Brussels after an acrimonious meeting of EU leaders last week.

Her plan to keep a close trading relationship with the EU on goods, protect manufacturing jobs and resolve arguments over the borders of Northern Ireland, while ending unrestricted immigration from the EU, was the only way forward.

"There is no other plan that protects jobs and livelihoods and also meets our commitments in Northern Ireland, while respecting how people voted in the largest democratic exercise in our history," May will say, referring to the 2016 vote.

"I am confident we can reach a deal about our future relationship. The prize is great: with the conclusion of the negotiations over the coming weeks ... business can look forward to the post-Brexit world with confidence."

Britain will have one of the world's most business-friendly economies after Brexit, she said.

"My message today is that a post-Brexit Britain will be an unequivocally pro-business Britain," May will say. She will pledge to deliver an economy that is "knowledge-rich, highly innovative, highly skilled and high quality but with low tax and smart regulation."

She also condemned policies unveiled by the opposition Labour Party at its annual conference this week.

"Frankly what we see is policies that would not be good for our economy, policies that would, as we've heard from others in business, lead to loss of jobs, and probably loss of investment."

Labour's finance spokesman John McDonnell announced on Monday that he wanted large firms to transfer a portion of their shares into a fund that would then pay out dividends to workers. The plan was swiftly criticised by business lobby groups.

"That's not helpful for people - that's putting his hand in people's pockets," May said.

(Reporting by William James; Editing by Elisabeth O'Leary and Mark Heinrich) ((elizabeth.oleary@tr.com; +44 131 248 9208; Reuters Messaging: elizabeth.oleary.thomsonreuters.com@reuters.net))