The group will release a greatest-hits album and kick off an 11-show world tour in December, it was announced in London Thursday. (See a video below.)
The two-month tour will begin Dec. 7 in L.A. and include concerts in Las Vegas, New York City, London, Cologne, Madrid, Beijing, Hong Kong, Sydney, Capetown and Buenos Aires.
"We are celebrating the past!" said Geri "Ginger" Halliwell at London's O2 Arena, when she and Victoria "Posh" Beckham, Melanie "Scary" Brown, Emma "Baby" Bunton and Melanie "Sporty" Chisholm were introduced on stage together for the first time since 1998.
"I want to be a Spice Girl again," said Bunton. "We are like sisters and we have our arguments, but by the end of the day we get back together."
Actor Richard E. Grant, who played the group's manager in their 1997 movie Spice World, introduced the band at the press conference after a video montage of their greatest moments played on screen.
"We are going to celebrate the past, do a small tour and that will probably be it," said Beckham, who had just returned from an Asian vacation with husband David after they said adios to their home in Spain on June 18. "Our priority is our families."
The Spice Girls first conquered the world after their Svengali manager, American Idol creator Simon Fuller, launched their first catchy tune, "Wannabe" in 1996. But the group fired Fuller in 1997; Halliwell quit a year later and the remaining four parted ways in early 2001.
Sources first told PEOPLE about the reunion plans in early June.
The Girls have been busy lately: Brown welcomed a daughter, Angel Iris, in April; Halliwell had a baby girl, Bluebell Madonna, in May; and Bunton is expecting her first child in August. Mother-of-three Beckham is moving to Beverly Hills on July 12 ahead of her NBC show airing four days later.
Referring to the baby boom, Beckham added, "We will definitely have a huge creche on tour."
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