North Korea has been warned it faces fresh sanctions if it goes ahead with a predicted missile test in the escalating nuclear stand-off with its neighbours and their Western allies.

Following talks in London of foreign ministers from the G8 industrialised nations, Foreign Secretary William Hague said they had committed themselves to "further significant measures" if the test went ahead.

"Clearly what we are talking about is in the field of sanctions. We would discuss such measures at the UN Security Council," said Mr Hague.

In the final communique, the ministers condemned in the "strongest possible terms" Pyongyang's continuing nuclear and ballistic missile programmes in defiance of Security Council resolutions.

They warned the regime's "aggressive rhetoric" would only serve to deepen the country's isolation and urged it to join "credible and authentic multilateral talks" on denuclearisation.

Following the talks at Lancaster House, US Secretary of State John Kerry headed off to the region for talks with key allies including South Korea.

In the latest ratcheting up of its rhetoric, North Korea said "powerful striking means" had been put on standby for a missile launch "and the co-ordinates of targets put into the warheads".