The 'Wannabe' hitmakers are expected to unveil dates for an upcoming stadium tour and though the 42-year-old singer - who will be joined by Geri Horner, 46, Mel C, 44, and Mel B, 43, in the reunited band - refused to talk about their future plans, she did promise fans won't have to wait long for some ''brilliant'' news.
Speaking on the 'Heart Breakfast' show she co-hosts with Jamie Theakston, she said: ''It's so exciting.
''Everything will be announced just after three o clock today on social media. You can go to @spicegirls but don't look at me anymore because I might just blurt it all out.
''After 3 o'clock today you will find out everything. I just want it out there. It will be brilliant.''
It has been claimed the quartet - who won't be joined in the reunion by fifth Spice Girl Victoria Beckham - will make their announcement in a social media video post that pokes fun at their group personas.
The tour is set to take place next summer and fans will be able to buy tickets in just a few days time.
A source told The Sun newspaper: ''Girl power is back.
''This is the biggest music comeback of the decade and tickets are expected to sell like hot cakes when they go on sale at the weekend.''
The band - who released their chart-topping debut single 'Wannabe' in 1996 - have not performed together since the London Olympics closing ceremony in 2012.
They went on hiatus in 2000, two years after Geri quit the band, and reunited for a tour in 2007 before going their separate ways again.
Following months of speculation the quintet were getting back together, it was claimed in June that a deal for a tour had collapsed after Victoria - who was known as Posh Spice - pulled out.
A source said at the time: ''The Spice Girls are in disarray. While Victoria has always insisted she'd never tour, the others believed manager Simon Fuller would get her on board.
''They had a £150million proposal in the offing - with a headline performance at Wembley - and even Mel C, who had previously been reluctant, was signed up.''
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