Coldplay frontman Chris Martin says the band aren't yet confident enough to play stadiums.

Writing on the band's website, Martin said Coldplay are “still trying to figure out how to make a room full of 10,000 people as exciting as possible, let alone a stadium.

“To me an arena feels like the perfect size canvas, so we're trying to master that," he added.

The UK leg of Coldplay's world tour, which includes two nights at the O2 Arena in London, will take place in December.

And Martin said that fan's attending the gigs can expect a fantastic show.

“If you come to our concert, you'll see the most magical balls you've ever seen. And ours is the first concert in the world to feature them,” he said.

It's also been announced that ticket holders for each of the band's UK dates will receive a free copy of the unreleased track 'Goldrush'.

The song features vocals from the band's drummer Will Champion.

(by Jason Gregory)