British Prime Minister Theresa May | Jack Taylor/Getty Images Theresa May pledges lowest business tax rate in G20 post Brexit UK will be ‘unequivocally pro-business,’ prime minister says.

NEW YORK — Theresa May will pitch post-Brexit Britain as a “low tax and smart regulation” economy Wednesday in a speech to business leaders in New York that will promise the lowest rate of corporation tax in the G20.

The U.K. prime minister will tell the Bloomberg Global Business Forum that the U.K. will be “unequivocally pro-business” when it leaves the European Union.

Business leaders have become increasingly frustrated with the U.K. government over the uncertainty around its Brexit plans, and what they regard as insufficient planning for a no-deal Brexit.

Following the acrimonious summit in Salzburg, Austria, last week at which EU leaders firmly rejected May's Brexit plan, Carolyn Fairbairn, director general the Confederation of British Industry, which speaks on behalf of 190,000 businesses, said that both sides need to compromise in the Brexit talks.

“The stakes could not be higher. Jobs, wages and living standards are at risk, on both sides of the Channel," she said. “With time slipping away, employers and employees alike need to see constructive dialogue. Pragmatism must come before politics. Every day lost in rhetoric is lost investment and lost jobs.”

"Whatever your business, investing in a post-Brexit Britain will give you the lowest rate of corporation tax in the G20" — British Prime Minister Theresa May

But May will say that she is “fully confident” the U.K. can secure a deal with the European Union, though she will warn the coming weeks will be “critical,” according to extracts of the speech issued by Downing Street.

“With the conclusion of the negotiations over the coming weeks, the certainty of an implementation period in which to adapt to the new arrangements, and the guarantee of frictionless trade with the EU in the future, business can look forward to the post-Brexit world with confidence,” she will say.

Her room to carve a niche for the U.K. as an economy with more business-friendly regulations will be limited though if the final Brexit deal ends up close to the plan agreed by her Cabinet in July at her Chequers country residence. Under that plan, the U.K. will remain bound by the EU's rules on goods trade and the EU is demanding further concessions that would bring Britain even closer to its regulatory orbit.

May's Brexiteer colleagues are urging her to opt for a looser Canada-style trade deal that would allow the British economy to diverge further from Brussels' rules, potentially allowing it to slash environmental and worker regulations to attract companies.

The U.K. prime minister said she is “absolutely committed to delivering continuity” in existing bilateral relationships, and forging “dynamic and ambitious” free-trade agreements with “old friends and new allies alike.”

And she will pledge that she has a plan to deliver a “knowledge-rich, highly innovative, highly skilled and high quality, but with low tax and smart regulation” economy.

“Whatever your business, investing in a post-Brexit Britain will give you the lowest rate of corporation tax in the G20. You will access service industries and a financial center in London that are the envy of the world, the best universities, strong institutions, a sound approach to public finance and a consistent and dependable approach to high standards but intelligent regulation,” she will say.