THOUSANDS of North-East jobs will be in serious jeopardy if Britain’s “umbilical cord” with the EU is severed, Prime Minister David Cameron has warned.

Mr Cameron said a Brexit could see at least 100,000 people facing employment misery as companies rein back investment to cover trade losses.

However, the Vote Leave campaign has decried the Conservative leader, saying businesses will still be able to successfully export to the Continent without EU interference.

It also claimed the Prime Minister’s rhetoric harks back to unfounded worries over the UK’s reluctance to join the Euro.

Mr Cameron voiced his concerns during a visit Hitachi Rail Europe’s £82m trainbuilding factory, in Newton Aycliffe, County Durham.

The Japanese multinational, which will soon employ more than 700 people and is making rolling stock for the East Coast and Great Western lines under the Government’s Intercity Express Programme, has long said it may be forced to re-think UK investment in a Brexit.

Car maker Nissan, the North-East’s largest private employer with nearly 7,000 staff in Sunderland, has also warned it may scale back spending in any EU departure.

Referring to the North-East’s strong balance of trade, emphasised this week by figures showing £1.9bn worth of goods left the region for the EU in the first quarter, Mr Cameron said it was foolish to believe Britain can forge better commerce agreements outside the organisation.

He said: “Listen to the nine out of ten economists, the Bank of England and the Treasury; they are unanimous our economy would be stronger in the EU.

“You are obviously going to have better access to your local market of 500 million people if you are inside the organisation that runs it and sets the rules.

“It’s not surprising the big investors would like us to stay because they come here for the skilled workforce, excellent labour relations and industrial history, but also because we are part of the single market.

“If we were outside the EU and had to pay tariffs its common sense we would make less, sell less and employ less.

“There are something like 100,000 jobs in the North-East dependent on trade with Europe.

“There is an absolute umbilical cord linking the single market and jobs and livelihoods here in the North-East.

“My very strong message is don’t cut that cord; this is about jobs."

However, Leave supporter John Elliott, founder and chairman of Aycliffe-based washer and dehumidifier maker, Ebac, said Mr Cameron’s claims were baseless.

He added: “Hitachi came to the North-East in order to supply the UK market with trains; that is not going to change if we leave the EU.

“Hitachi’s biggest client in the UK is the Government, so it’s no surprise they’re dancing to their tune.

“We've heard this all before.

“Large multinationals, such as Nissan, said they would leave if we didn't join the Euro, but they didn't.

“Hitachi has said all we need is a free trade deal with the EU, which we will have when we vote to leave on June 23.”

Yet Mr Cameron said Hitachi’s worries over a Brexit were proof the situation was not so simple.

He said the business, which will also make rolling stock for Scottish lines and FirstGroup’s TransPennine Express franchise, needs the EU to continue its growth.

He said: “This is perhaps one of the best examples of this whole argument.

“They are making fantastic trains, which are going to help with the modernisation of our railway lines, but there is a huge opportunity for breaking into the European market and making trains that will run on German, Italian or Spanish lines.

“There can be no doubt there is a chance of getting those orders if you are in the EU.

“If you are out of the single market it would be far more difficult if Hitachi wants to beat German manufacturers to make trains for Germany.”

The Prime Minister also played down fears for the Government post-referendum, as divisions between Mr Cameron and senior ministers and Leave campaigners, such as Boris Johnson, threaten to unsettle the party.

He added: “We must obey the will of the people and come back together and get on with the important business of governing the country and delivering the jobs, skills, schools and hospitals we need.”