After spending almost every minute of the past two months together, playing dates across the US, the UK and Canada, the Spice Girls have been driven to bickering and squabbling. And the pressure of their gruelling schedule and endless performances finally pushed the fivesome to their limits.

Sick of Victoria's diva behaviour and constant name dropping, Mel B decided she'd had enough and refused to continue the tour. Quick on her heels was Mel C, who's fed up with feeling like an outsider as the only childless Spice Girl.

'Mel B spent the weeks before the tour kicked off as top of the tree, doing brilliantly on [US] Dancing with the Stars, and found it really hard to be plunged into Victoria's shadow once the tour started,' a source says.

'Whenever Posh came on stage or sang, the audience would scream and go mental to the degree that you couldn't even hear what she was singing. And although she didn't really do anything in her solo performances other than pout in a pair of sunglasses, she got more cheers than Mel B did for her performances. Mel
really had enough of it and that kept leading to arguments.'

Victoria's diva behaviour, including her incessant celebrity name dropping, only added to the animosity already brewing due to her obvious position as queen of the Spice Girls.

The source continues: 'The simple truth is that none of the other Spice Girls are as famous as Victoria now and, although they all know that, they found it very difficult to take. She'd be swanning around in designer clothes, talking endlessly about Katie and Tom or J.Lo and it started to get on their nerves.

She's constantly on her mobile and talking to assistants. The other girls have less of an ego, and everyone has found it hard to deal with. Mel B was used to being important again and really resented Victoria for making her feel like a nobody.'

As tensions mounted and nerves began to fray in the Spice camp, Mel B decided once and for all the tour was simply not worth the effort.

'She's newly married and didn't enjoy spending so much time away from home. In the past few weeks it had become less fun.

She said she'd just had enough,' the source adds.

But it wasn't only Mel B who pulled the plug on the extended version of the Spice Girls tour. Mel C had also reached the end of her tether and seconded the decision to call it quits.

Another source close to the band says: 'Mel C wasn't one hundred per cent convinced the tour was a good idea in the first place and, while she's enjoyed parts of it and loves performing more than anything, she's been made to feel like an outsider.

'She's the only one who hasn't had a baby and, while that's not a problem for her in her personal life, a huge segment of the show was dedicated to the others' kids and the fact they are mums - and she really just felt left out,' the source continues.

'The others all had their kids with them at various points in the journey too, and there were loads of concessions made to make sure they were free at certain times to do important things with their babies. She completely understood and didn't resent them for spending time with their children, but it did feel a bit like she was the least significant, and that the things she needed were
not as important because she didn't have a child.'

The stars have already earned an estimated $22 million each from their tour to date and, according to sources, didn't think it necessary to string out the situation any further.

The girls had always insisted the reunion wasn't about money - it was about the fans. But one music industry insider says this claim verges on hypocrisy, considering the enormous fees the group charged for tickets.

However, a source close to the girls insists that money, while an obvious bonus, wasn't the drive behind the show.

'For most of them - particularly Victoria, Geri and Mel B - it was about self image and that desire for public adoration, but it's turned sour for Mel B who, after her TV success in the US, now thinks she'd do better on her own anyway.'

The source continues: 'Mel C had got used to having her life operate on a smaller scale, which is why she was concerned about getting involved in the first place. Once things started to turn a bit nasty, other insecurities began to set in - she was feeling insecure about her figure and getting pulled into that competitive thing.

Geri and Victoria are so hung up on what they eat and how they stay slim, it's not healthy for her. She was relieved to say goodbye to it all.'

The final gig of the tour will now be in Toronto on February 26 and will probably be the last time they perform together.

In their official statement they offered Aussie fans a glimmer
of hope: 'Really sorry if we didn't get to see you this time around. We all have other commitments in our lives. But who knows what will happen? We've had an amazing time.'

But Victoria has other ideas. 'I'm not in the music industry any more,' she says. 'I'm in the fashion industry. I'm putting together a team of people now, so it'll be my main project when I finish this tour.'