Biffy Clyro and System Of A Down added to Reading and Leeds festival line-up

The August gigs will be both Eminem and Biffy Clyro's only UK festival appearances this year

Simon Neil of Biffy Clyro performs on the main stage during day two of the Isle of Wight Festival 2010 at Seaclose Park (Getty Images)

Scottish trio Biffy Clyro will headline at this year's Reading and Leeds festivals.

The rockers, whose album Opposites, is currently number one in the UK charts, will appear on the Main Stage joining previously announced headline acts Alt-J and Eminem.

"Reading always felt like such an exotic festival. Even though it's been around since the 70s, it just really seemed to come alive in the 90s. I think that's when it became the cultural moment that it is now, and the fixture that it is in the calendar," Biffy Clyro frontman Simon Neil told NME.

"It's just f****** bizarre. I still can't get my head round it."

The gigs on 23-25 August will by Biffy Clyro and Eminem's sole UK festival appearances of 2013.

Festival organisers today also announced that System Of A Down, who have only played a handful of gigs since they reformed in 2010, will make an appearance on the Main Stage at Reading and Leeds.

Other new names added to the line-up include Jake Bugg, Fall Out Boy, Foals and metal band Bring Me The Horison.

Acts previously confirmed to appear include Deftones, Boy Better Know ft. Wiley, JME and Skepta and Sub Focus.

A further headline act is yet to be announced.

Read an interview with Biffy Clyro in this Saturday's Radar magazine