Brown and Murphy started dating in June, but the Hollywood star cut all ties with the former Spice Girl earlier this month and is now demanding a DNA test to determine whether or not he's the father of her unborn baby.
According to reports, Halliwell has been comforting Brown since the break up, and sympathises with the pop singer because she went through a similar experience with daughter Bluebell.
Halliwell became estranged from the baby's father Sacha Gervasi before seven-month old Bluebell was born.A friend of Halliwell says: "The fact that Geri was in a similar position to Mel, with an acrimonious relationship with the father of her child, is an instant bond between them. Geri feels she understands what Mel is going through."
The former bandmates fell out several times while in the band, and most recently Halliwell blamed Brown for scuppering the proposed Spice Girls reunion at last years' Live 8 show in London.