Unions have sought urgent talks with Tata Steel after the owner of the Port Talbot steelworks shocked workers with plans to cut 3,000 jobs across Europe.

The announcement, the latest sign of the difficulties facing the steel industry, was made late on Monday night without any consultation with worker representatives in the UK.

Two-thirds of the job losses will be in office-based jobs, Tata said. It is understood the majority will fall on operations in mainland Europe.

However, the announcement cast a shadow over the Port Talbot steelworks, the largest in the UK, which employs about 4,000 people. It comes after Tata Steel in September announced the closure of another South Wales factory in Newport.

Tata blamed declining EU steel demand and global overcapacity for the job cuts, which it said had been “compounded by trade conflicts which have turned the European market into a dumping ground for the world’s excess steel capacity”. Tata also cited an increase in the cost of emissions allowances for the heavily polluting industry.

Roy Rickhuss, general secretary of Community, said the steelworkers’ trade union would fight to hold Tata Steel to a jobs guarantee that lasts until 2021.

“This is a shocking announcement, which will worry many steelworkers and their families in the UK and across Europe,” he said. “This news has been badly handled and the company should hang its head in shame with the way this development has been communicated.”

Tata Steel’s British operations have declined in recent years. In 2016 Tata sold its long products division to private equity firm Greybull Capital for £1 and that business was renamed as British Steel, which has since collapsed and been bought by Chinese group Jingye. In 2017 Tata sold its specialist steel operations to Liberty House.

The cuts come after Tata failed to secure a merger with German steel rival Thyssenkrupp. The European commission said the deal would have diminished competition, despite the companies hopes that cost sharing could improve profitability.