North Korea says last week's explosion in a remote northern area was part of a hydro-electric project.
According to the BBC, Foreign Minister Paek Nam-sun told London's Foreign Office minister Bill Rammell, who was visiting North Korea, that the blast was the deliberate demolition of a mountain for the project.
South Korean officials yesterday confirmed indications of a large explosions in the region bordering China on the night of September 8th and early morning of September 9th.
There has been no explanation by the North's official media of the explosion.
Initial reports of a possible nuclear test had been questioned by South Korean and US officials who said there was a lack of signature signs.
Mr Rammell is the highest British official to visit Pyongyang and he had been expected to meet the North's leader, Mr Kim Jong-il.