The concept timepiece, devised by the Bulletin of the Atomic Scientists now stands at six minutes to the hour.

The group said it made the decision to move the clock back because of a more "hopeful state of world affairs".

Lawrence Krauss, co-chair of the BAS board of sponsors, warned scientists that there was still much to be done.

"We urge leaders to fulfill the promise of a nuclear weapon-free world and to act now to slow the pace of climate change," he said.

"We are mindful of the fact that the clock is ticking," he added.