The Spice Girls today confirmed one of the pop world's worst-kept secrets when the girl group announced they would reunite for a world tour.

At a press conference in the O2, London -- formerly the Millennium Dome -- the five-piece group announced they will perform 11 dates in eight countries, beginning with a concert Dec. 7 in Los Angeles. The tour will press on through Las Vegas (Dec. 8), New York (11), London (15), Cologne (20), Madrid (23), Beijing (Jan. 10), Hong Kong (12), Sydney (17), Cape Town (20) and Buenos Aries (21).

Today was the first time all five singers -- Geri "Ginger" Halliwell, Melanie "Sporty" Chisholm, Melanie "Scary" Brown, Victoria "Posh" Beckham and Emma "Baby" Bunton - had been seen in public together since 1998, when Halliwell left the group.

But, in front of the world's media, the girls were soon back in the old "Girl Power" routine that made them globally famous the first time around.

One male reporter was mocked for looking "like Britney Spears' ex-husband," and another forced to remove his shirt after he dared to suggest the fivesome -- now more Spice Women than Spice Girls -- might not be "fit enough" for a world tour. Such antics caused chaos among the paparazzi, with one cameraman injured as he fell off his ladder during the surge for photos.

There was little sign of the old tensions within the group. Even when Halliwell threatened to dominate proceedings, Beckham diffused things by quipping: "She just appreciates the fact that we've let her back in [the group]."

The tour will support the November release of a first-ever greatest hits compilation, through Virgin Records. Mel C gave Virgin's parent company EMI the credit for getting the group back together -- while Halliwell and Beckham also paid tribute to manager Simon Fuller's involvement.

"You need a man with balls of steel to get us back together," joked Ginger.

The band say the reunion is unlikely to become permanent.

"We just want our kids to see what we do," said Beckham, who is married to soccer superstar David. "I might even get to be the cool one in my family for once."

Beyond the Beckham brood, however, the girls were less sure who might attend the concerts.

"We're celebrating the past," admitted Halliwell. "But if new fans want to come along that's fantastic."

One gig the girls are unlikely to play is this weekend's Princess Diana concert in London, despite strong rumours they would appear. With Emma Bunton due to give birth to a Baby Spice of her own any day now, the band claimed such an appearance would be too risky.

Filmmaker Bob Smeaton ("Beatles Anthology", "Who's Next") will oversee the official documentary on the reformed band, which will be distributed worldwide at an undisclosed date.

The press conference was hosted by actor Richard E. Grant, who played the band's manager in "Spiceworld: The Movie," who described the band's commercial achievements as "Beatles-esque."

The Spice Girls became a global phenomenon on the release of their first single, "Wannabe," from 1996, which went on to grab the No. 1 slot on 31 national singles charts, according to EMI. The band has gone on to sell 55 million records, and grab the top spot on the Official U.K. Singles Chart on nine occasions.