Britain's biggest steel maker has urged Labour to step up efforts to finalise a US trade deal as the industry remains saddled with double digit tariffs.

Rajesh Nair, boss of Tata Steel UK, said a deal with Washington is needed 'as soon as possible'.

There is growing frustration that an agreement made last month has yet to take effect.

Additional steel and aluminium tariffs remain at 25 per cent.

The UK, however, was spared a recent doubling of the rate to 50 per cent, which hit other countries. Doubt continues over whether Indian-owned Tata will benefit from either exemption.

That is because it imports steel from sister companies in India and Europe for finishing in the UK. US rules state that steel must be 'melted and poured' in the country they are imported from.

Nair said it was 'critical for our business that melted and poured in the UK is not a requirement to access the steel quotas in any future trade deal'.