THERESA May has been urged to prove Britain is a top military power by spending more to counter Russia’s Arctic threat.

MPs on a cross-party Commons committee said Russia is re-opening manned bases along its Arctic coastline and its islands as well as building up forces at borders.

Piling pressure on the PM, the MPs said the definition of a “Tier One” defence nation is “one which has the ability to deploy a full range of capabilities anywhere in the world”.

It went on: “This includes the unique operating environment of the Arctic and the High North.”

The committee urged the Government to show “greater ambition and apply more resources” to tackle Russia’s “aggressive” expansion in the region.

Chairwoman Madeleine Moon warned a comprehensive strategy was needed.

She said: “The changing security environment in the Arctic and the High North is a matter of growing significance to the UK.”

A row blew up between Mrs May and Defence Secretary Gavin Williamson this summer after she refused to confirm if Britain will remain a Tier One defence power.