Mel C is reportedly "consulting lawyers" to see whether the Spice Girls can reunite without her and Victoria Beckham.
While the 42-year-old singer is in regular text and phone contact with Geri Horner, Mel B and Emma Bunton, she is said to be considering legal action against the trio who recently announced plans to reform the girl band in honour of their 20th anniversary.
A source said: "Mel has told the other girls she is consulting lawyers about whether the reunion can go ahead without her.
"She believes she brought music credibility to the group and there is no Spice Girls without her. The other girls are in regular text and phone contact with her."
The trio have decided against using the moniker GEM – meaning Geri, Emma and Mel – for their reunited group but are still planning to go ahead with their reunion.
The source said: "There was talk of using the nickname GEM but they’ve decided against that because the strength is through the Spice brand.
"The girls are pressing ahead with their reunion plans as they were before."
While Mel is thought to be considering legal action, Victoria is said to have been "really supportive" about the idea.
The source added to The Sun newspaper: "Victoria has told the girls to go for it.
"She’s been really lovely and supportive, which has been a relief to them."
Last month, a Spice Girls track called ‘Song For Her’ was leaked, their first material for nine years.
A source said at the time: "Obviously the girls have been recording in the studio over the past few months.
"The plan is very much for there to be new music."
Geri, Emma and Mel B are expected to perform a one-off show in London’s Hyde Park next July.