Biffy Clyro are ''sh***ing it'' about performing at Reading and Leeds 2013.

The 'Black Chandelier' band may have performed at the UK festivals seven times already, but are nervous about their first headlining appearance this August.

Frontman Simon Neil told NME magazine: ''You kind of learn when to be really intense and when to just let the crowd take over. But we are sh***ing it.

''It's an important slot and I don't want it to be anything less than amazing because we've been there in the crowd and we know it has to elevate things to a peak.''

Biffy Clyro have steadily built up to fame since forming in 1995, with their 2009 album 'Only Revolutions' peaking at number three in the UK album charts. Their latest record, 'Opposites' then beat that to claim top spot on the charts earlier this year.

The serious approach to headlining the festival will reflect the effort and ''grown up'' approach the band took when recording double album 'Opposites'.

Simon has previously said: ''With this album we've had a more grown-up approach. The only late nights we have are in here. We take our responsibilities seriously and hate to waste studio time as that means wasting money. We are always aware of that.''

Reading and Leeds will kick off on August 23 and will also include headline sets from Green Day and Eminem.