LONDON • Prime Minister Theresa May pledged yesterday to fight for the "precious, precious union" of the United Kingdom, unveiling what she called her "Plan for Britain" with a warning to Scotland not to pursue its independence plans.

Mrs May, appointed Prime Minister soon after Britain voted to leave the European Union in a referendum in June last year, said she would negotiate a Brexit deal for the whole country, but needed everyone to pull together to get the best outcome.

Facing two years of what are likely to be difficult talks for Britain once she triggers the Brexit process at the end of this month, Mrs May wants to stamp her authority on a new agenda for the country, but is struggling to repair the deep divisions exposed by the Brexit vote.

Nationalists in Scotland have condemned her move to block their demands for a new independence referendum before the EU talks end as an "outrage", and Northern Ireland's largest Irish nationalist party says it wants a vote on splitting from Britain after both regions voted to stay in the bloc.

"The coming negotiations with the EU will be vital for everyone in the United Kingdom... It is essential that we get the right deal, and that all of our efforts and energies as a country are focused on that outcome," Mrs May told her party at the Conservative Spring Forum in the Welsh capital of Cardiff.

"We need to do so united, as one United Kingdom, all pulling together to get the best outcome," she said, promising to ensure that all the voices and interests in England, Scotland, Wales and Northern Ireland are represented.

Mrs May was applauded as she repeated that she would give notice to the EU in the next two weeks that the United Kingdom is leaving it for good.

"I will always fight to strengthen and sustain this precious, precious union," she said.

It will not be an easy fight. The ruling Scottish National Party (SNP) in Edinburgh has refused to back down over its demand for a new independence vote after Mrs May said: "Now is not the time."

Kicking off the SNP spring conference in Aberdeen, Deputy Leader Angus Robertson said Mrs May has no right to deny Scotland another referendum. "Let there be no doubt - Scotland will have its referendum and the people of this country will have their choice. They will not be denied their say," Mr Robertson told SNP delegates. "No United Kingdom prime minister should dare to stand in the way of Scotland's democracy."

Some lawmakers suggest Mrs May's tough stance could spur support for a new referendum.

The government wants to avoid having to spread its resources between defending the integrity of the three-centuries-old union and securing a Brexit deal that is as advantageous as possible to Britain.

Mrs May did not linger on Brexit in her speech, saying simply she would adopt a "phased approach" to deliver a "smooth and orderly Brexit" and offer certainty wherever possible. Instead, she wanted to reinforce her pitch for the political centre ground and move the conversation away from the EU and Scotland.

She pledged to boost technical training, reform energy markets and increase selective schools. "Our Plan for Britain is a plan for a brighter future," she said. "A plan to make the most of the opportunities ahead and to build a stronger, fairer Britain that is more united and more outward-looking."

REUTERS, BLOOMBERG