The new date will be set to accommodate bands who have pledged their support, but also further bands of significant stature whose current commitments did not allow them to perform this month.

A new date is being negotiated by the organisers with bands and the Millennium Stadium to ensure the concert maximises impact of the crucial climate change message.

"Support is growing daily for the concert and cause and a new date will allow us to create the greatest impact from the best bill of talent," said Mr Mathres, co-founder of the Climate Change Now initiative. "We apologise wholeheartedly for any inconvenience caused by the change of date but we can assure those who have already purchased tickets that the event will still take place at the Millennium Stadium.

"Our aim is to engage as many people as we can, around the world in actively tackling climate change. The last few weeks has seen a ground swell of support for the campaign and has opened up opportunities to spread the important message of Climate Change Now, even louder and further.

"We cannot pass up this opportunity and look forward to a year of positive public action to tackle climate change."

Millennium Stadium chief executive Paul Sergeant added: "Whilst we acknowledge it is disappointing for those who have already bought tickets for the event, if the event can be made bigger and better and attract more of the highest profile names in the music industry then it is the correct decision to make.

"Music lovers are assured the event will still take place at the Millennium Stadium and we’re working with the event organisers to find a suitable date later in the year."