International touring rock festival Sonishphere will expand to three days in the U.K. in 2010 following its launch this summer, with headline appearances from Iron Maiden and Rammstein.

The festival will call at 11 international locations next summer. In addition to its U.K. dates, Sonisphere will be staged in Warsaw (June 16), Stockholm (Aug. 7), Pori in Finland (Aug. 7-8), Zurich (June 18), Prague (June 19), Sofia (June 22-23), Athens (June 24), Bucharest (June 25-27), Istanbul (June 25-27) and Barcelona (July 10).

The U.K. leg of the event will return to Knebworth outside London, on July 30 to Aug. 1. It will be the only 2010 U.K. appearance for Iron Maiden, while German industrial act Rammstein will make their first - and only 2010 - U.K. Festival appearance.

"Knebworth has been the home of so many legendary concerts going back many years, it really will be a privilege to play there," said Iron Maiden's Bruce Dickinson in a statement.

Other acts confirmed for Sonisphere at Knebworth include Slayer, Motley Crue, the Cult, Anthrax, Iggy and the Stooges and Alice Cooper.

Metallica has been confirmed to headline in Poland, with Anthrax, Slayer, Mastodon and Behemoth also on the bill; the Swedish leg will feature headliners Iron Maiden alongside Motley Crue, Alice Cooper, Iggy and the Stooges, Slayer and Anthrax; and the Finland line-up will feature Iron Maiden, HIM, Motley Crue, Alice Cooper, Iggy and the Stooges, Slayer, the Cult, Anthrax and Heaven & Hell.

Sonisphere was launched this summer by Stuart Galbraith, series producer and director and CEO of Kilimanjaro Live, and John Jackson, festival creator and director and Metallica's booking agent at K2 since 1985. AEG, which backs Kilimanjaro, also supported the new festival.