The Spice Girls, who burst on to the music scene with "girl power" and attitude in the 1990s, said on Thursday they had reunited for an 11-city world tour starting in Los Angeles this December.

Ginger, Sporty, Posh, Scary and a heavily pregnant Baby Spice told a packed press conference in London that the tour would take place in December and January and would be accompanied by a greatest hits album and a television documentary about the band.  "Girl power is back, we're going on the road, we're touring the world," Emma "Baby Spice" Bunton said in a promotional video shown to the press before the five girls appeared on stage at London's 02 arena. Their Web site www.thespicegirls.com provided a link for fans to buy tickets to the shows in Los Angeles, Las Vegas, New York, London, Koln, Madrid, Beijing, Hong Kong, Sydney, Cape Town and Buenos Aires. When asked why she had dropped her previous resistance to a reunion, Melanie "Sporty Spice" Chisholm replied: "A girl's allowed to change her mind. This is something that we've only seriously started discussing this year."

The five-member band is the latest in a long line of pop acts to bury past differences and reform, hoping for success where many others have failed.

"For me it's about celebrating the past, enjoying each other, it's about our fans. It felt the right time -- it's kind of now or never," Gerri "Ginger Spice" Halliwell said.

The Spice Girls boasted album sales of 55 million during their brief career, and hits including "Wannabe" and "Say You'll Be There" topped charts across the globe.

But their success was shortlived. Halliwell left in 1998, only four years after The Spice Girls were created, and the remaining band members went their separate ways after releasing the album "Forever" in 2000.

All now in their 30s, the singers embarked on solo careers with varying degrees of success, and rumours that they may one day reform have circulated for years.