Washington is lobbying Britain to send more troops back to Afghanistan, with the Pentagon concerned the UK’s current plans to back Donald Trump’s mini surge in the country are “not enough”.

The US ambassador to Nato said today that America wants Nato allies to send a total of an extra 1,000 troops to help in the battle against the resurgent Taliban, Isil and al Qaeda.

Pentagon chiefs are understood to be unimpressed with Britain’s pledge over the summer to boost its own contingent of trainers and security forces by 85 to a total of 600.

The MoD said last night troop levels were under constant review.

Mr Trump announced in August that he would send thousands more troops to the country but demanded they be accompanied by reinforcements from America’s allies.

Kay Bailey Hutchison, US ambassador to Nato, said the other forces were needed to join roughly 3,000 US troops who are already on their way to Afghanistan.

A series of visiting senior US officials are believed to have raised the issue in London in recent months.