The Sonisphere Knebworth festival, which is the only date scheduled for a Queen performance featuring Adam Lambert, has been cancelled.

Due to unforseen difficulties, plans for the Stevenage, England event were scrapped, according to organizers.

It is with very heavy hearts and much regret that we announce the cancellation of Sonisphere Knebworth 2012, reads a statement on the festival's website. Putting the festival together in what is proving to be a very challenging year was more difficult than we anticipated. Unfortunately circumstances have dictated that we would be unable to run the festival to a standard that both the artists and that Sonisphere's audience would rightly expect.

KISS and Marilyn Manson were also slated to perform at the three-day festival, scheduled for July 6 to 8.

Meanwhile, Sonisphere events in Poland, Spain and Switzerland will go on as planned. Metallica will take Queen's place as the headlining act, supported by Evanescance, Faith No More, Flogging Molly, Mastodon, Andrew W.K., Incubus and the Darkness.

In February, Lambert shocked the world of rock  after revealing that he would be taking Freddie Mercury's place as Queen's frontman.

The intention is to pay tribute to Freddie and the band by singing some f*****g great songs. It's to keep the music alive for the fans and give it an energy that Freddie would have been proud of, he told the Daily Star at the time.

Lambert and Queen later revealed plans for a headlining set on day two of the traveling rock festival.

Both parties have yet to comment on the possibility of making plans for an alternate performance.