A NORTH-EAST steel maker says the UK's continued presence in the European Union (EU) will be a key factor to its future success.
Tata Steel, which employs 1,500 workers in the region, has responded to the Government's review into a potential withdrawal from the EU.
Bosses say leaving the EU will leave the UK isolated.
Tata is the world's 12th largest largest steel producer and has factories across the North-East, including its Teesside beam mill, in Redcar, which rolls and finishes construction steel sections.
A report said: “In revenue terms, about 50 per cent of the steel the firm produces in the UK is sold into continental Europe.
“As the largest single market in the world, the EU has a strong bargaining position in trade negotiations.
“Conversely, on its own, as a relatively small market, the UK would not be as attractive for third countries to negotiate with and would not have the same bargaining power.
“There would be a danger the UK would find itself isolated and without the necessary power to negotiate trade deals.”
Angelika Schneider, Liberal Democrats' lead North-East European candidate, said vital jobs would be at risk if the UK left the EU.
She said: “Many thousands of North-East jobs rely on us staying in Europe, securing access to the single market and opening up trade opportunities for local businesses.
“As Tata make clear, being part of the world's biggest trading bloc means we're able to negotiate much better deals with other countries than we could manage on our own.”
Tata's warning comes after bosses at Sunderland car maker Nissan and Newton Aycliffe-based train builder Hitachi Rail Europe called for the UK to remain in the EU.