"Following weeks of speculation, the Spice Girls are set to make an official announcement to the world regarding future plans on Thursday, June 28," said a statement by their management company, 19 Entertainment.
"Details regarding the announcement will be released in the coming days," said the statement, released Friday.
The Spice Girls formed in 1994, eventually splitting in 2001.
Melanie Chisholm, who had opposed a reunion, recently told the British Broadcasting Corp. that she had changed her mind.
"For the first time ever, there is some truth in the rumors. We've been discussing it and it could possibly happen," the 33-year-old singer, aka Sporty Spice, told BBC radio.
"I've always said, 'I don't want to do it, the past is the past. It was amazing, it was magical. We could never recreate it,' " Chisholm said. "But this year people have been talking about it and some of the girls have expressed an interest in doing it."
The Spice Girls also included Scary Spice (Melanie Brown), Posh Spice (Victoria Beckham), Baby Spice (Emma Bunton) and Ginger Spice (Geri Halliwell).
Their 2000 album, "Forever," had weak sales, and the Spice Girls began concentrating on their solo careers.