The UK is heavily reliant on imported diesel from the US. But with US voters also facing higher fuel costs ahead of the midterm elections in November, Trump has threatened to restrict diesel exports.

The UK has been discussing the US supply threats with the EU which is holding a meeting on Friday on the issue.

Banning exports would flood the US market with diesel, and could bring prices down significantly for American drivers.

But experts warn such a ban would put further pressure on diesel prices in other countries, unless they can access further supplies.