Ukraine is now the most heavily mined country on Earth and its army is suffering from a critical shortage of men and equipment able to clear the frontlines, the country’s defence minister has said, as soldiers spoke of heavy casualties in the engineering brigades.

In an urgent appeal to allies, Oleksii Reznikov told the Guardian his soldiers were unearthing five mines for every square metre in places, laid by Russian troops to try to thwart Ukraine’s counteroffensive.

He said the vast minefields could be traversed, but that it was critically important that allies “expand and expedite” the training already being provided by some nations, including Britain.