Slipknot has added a June 4 stop at the Rock in Rio-Lisbon festival to its 2004 tour calendar, which currently only features a handful of international stops.

Slipknot has added a June 4 stop at the Rock in Rio-Lisbon festival to its 2004 tour calendar, which currently only features a handful of international stops. The masked metal act is also slated to play Japan's Sonicmania Festival (Jan. 31 in Osaka and Feb. 1 in Tokyo) and a June 21 date in Amsterdam with Metallica.

As previously reported, Metallica will also play the Rock in Rio festival on June 4. Others slated to play the May 29-30 and June 3-6 event at the Bela Vista Parque in Lisbon include Guns N' Roses, Sting, Alejandro Sanz, Xutos & Pontapes, Ivete Sangalo and Rui Veloso.

Slipknot has spent the past few months in Los Angeles recording a new album at a mansion once owned by Harry Houdini and said to be haunted the famed magician. Rick Rubin is producing the nine-member Iowa-based act's fourth studio set, its third for Roadrunner. The as-yet-untitled work is due in the spring.

"I know that all bands say that their 'new' record is gonna be the best, but in all sincerity this is gonna show all the new bands how it's really done," drummer Joey Jordison (aka. No. 2) says. "We are comin' back to reclaim the crown of the world's most brutally honest and insane band."

Released in September 2001, the band's last album, "Iowa," debuted at No. 3 on The Billboard 200, besting a No. 51 peak for the previous year's self-titled Roadrunner debut. The albums have sold 852,000 and 1.6 million copies in the U.S., respectively, according to Nielsen SoundScan.

Here are Slipknot's upcoming tour dates:

Jan. 31: Osaka, Japan (Sonicmania Festival)
Feb. 1: Tokyo (Sonicmania Festival)
June 4: Lisbon (Rock in Rio-Lisbon)
June 21: Amsterdam (Amsterdam Arena)