THE Prime Minister's promise of an in/out referendum on Europe will increase economic uncertainty and put 140,000 North-East jobs at risk, critics claimed last night.

But leading Tories in the region defended David Cameron's announcement, saying it was the right approach to get the best deal possible for Britain - then let the country vote.

In a defining speech of his premiership, the Prime Minister pledged to negotiate a new settlement with Brussels and then give people the "simple choice" between staying in under those new terms, or leaving the EU.

The announcement was welcomed by Tory backbenchers who have long campaigned for a vote.

However, Labour MPs and union leaders in the region warned the referendum – potentially due in 2017 - would create four years of uncertainty for North-East businesses.

Judith Kirton-Darling, confederal secretary of the European TUC who is Middlesbrough based, claimed the pledge would undermine investment for many companies dependent on trade with European partners.

She added: “In the North-East alone, over 140,000 jobs are dependent on EU trade with over 63,000 of those in County Durham and Teesside. We cannot afford to lose a single one of them.

“David Cameron and Tory Eurosceptics are playing hard and fast with people's livelihoods in our region. It is deeply reckless.”

North Durham MP Kevan Jones said the referendum was “bad news” for the North-East economy.

“This will create four years of uncertainty for companies in the North East, who are already finding it tough in this economic climate.”

Fears of the announcement creating uncertainty were also expressed by North East Chamber of Commerce chief executive, James Ramsbotham.

He urged the Government to approach this issue with a “hard-headed economic assessment of the potential pros and cons”, adding: “If at any time this process starts to create damaging uncertainty we would expect Mr Cameron to act swiftly to secure the UK’s position in the global economy.”

But Stockton South Conservative MP James Wharton welcomed the announcement, saying Labour's claims of economic uncertainty were “utter rubbish”.

“This is exactly the right approach. We should get the best deal we possibly can on the table and then give the British people a choice.

“Whatever happens a renegotiation to bring back powers and strength Britain’s interests is welcome and by putting the conclusion of that process to the British people we can settle the matter for a generation.”

Foreign Secretary and Richmond MP William Hague also backed the referendum, which he claimed would set out Britain's approach on Europe for decades to come.

“I think this is something that will appeal to many people across many political parties,” he added.

In his speech in London, the Prime Minister said the Conservative manifesto for the 2015 general election would ask for a mandate to negotiate a new settlement for Britain in Europe, which will be put to voters in a referendum within the first half of the five-year parliament.

Mr Cameron said it was time for the EU to ditch the universal commitment to ever closer union and accept that members can decide for themselves how deeply they wanted to integrate.

Mr Cameron said it was his strong preference to enact these changes for the whole EU, not just Britain alone.

Standing in front of a backdrop with the slogan Britain and Europe, Mr Cameron said: “It is time for the British people to have their say. It is time to settle this European question in British politics.”

And he added: “When the referendum comes, let me say now that if we can negotiate such an arrangement, I will campaign for it with all my heart and soul.

“Because I believe something very deeply. That Britain's national interest is best served in a flexible, adaptable and open European Union and that such a European Union is best with Britain in it.”

Mr Cameron's speech came after months of pressure from Tory backbenchers unnerved by the surge in support for the Eurosceptic UK Independence Party (UKIP), which has regularly recorded ratings over ten per cent in recent polls.

UKIP Yorkshire MEP Godfrey Bloom claimed the Prime Minister's speech was a “devious attempt to kick the whole matter into the long grass”.

“It is based on him winning the General Election and a referendum would be five years down the line.

“In that time the EU will have caused further untold damage to our economy. We need an in-out referendum and we need it soon,” he added.