Geri Halliwell left the Spice Girls so she could concentrate on her breast cancer campaigns, she has told the BBC.

In her first British TV interview since the split, she told chat show host Michael Parkinson the Spice Girls' tight schedule would have prevented her from doing an interview on the issue, so she walked out on the spot.

Ms Halliwell had a lump removed from her chest at the age of 18 and has become a prominent campaigner since she left the group in May.

"The day I left the Spice Girls I wasn't planning to leave, it made me check out my own principles," she told Parkinson.

"I was meant to be doing the National Lottery show and the schedule wouldn't permit me to do a breast cancer interview and I thought, 'Hold on a minute, what are your principles?'

"So I had to question myself. That is the reason I left on that day - there was never a good day to leave."

She added she was always planning to leave the group anyway - and had told Melanie Brown, Melanie Chisholm, Victoria Adams and Emma Bunton four months earlier she was planning to quit in September 1998.

Halliwell added the split was still "quite tender in my heart" and her relationship with the others was "like a marriage".

She said: I fell in love completely, passionately, I needed it."

But she added: "Like one in three marriages, under the pressure of work schedules the marriage broke up, it imploded."

Halliwell added the decision to go was "nothing to do with any of the girls really".

She also spoke of her stint as a topless model before she was successful - which came back to haunt her at the height of her fame.

"To be honest it was boring. I found it very, very dull in the end. Standing there with the window open to keep your nipples firm was not good," she said.

Since leaving the Spice Girls Geri has signed a solo deal with EMI, and has already written lyrics for her songs.

She said: "It's totally schizophrenic with mood swings so that every woman in Britain will identify with it."

Many thanks to Kathryn for the excellent pics!!

Former Ginger Spice Geri Halliwell says she planned to quit the group all along but was prompted into early action because she would have been prevented from talking about breast cancer.

In her first British TV interview since the split, she said the Spice Girls' tight schedule would have stopped her from doing an interview about the issue close to her heart - so she left on the spot.

Geri said on BBC1's Parkinson that she had already told the rest of the band about her plans to go her own way four months later in September.

"The day I left the Spice Girls I wasn't planning to leave - it made me check out my principles," she told Michael Parkinson.

The night she quit in May she was due to perform on BBC1's midweek Lottery show and her absence was explained by illness.

"Actually, I was meant to be in this studio doing the National Lottery," she said, referring to Studio 6 at BBC Television Centre, "and the schedule wouldn't permit me to do a breast cancer interview and I thought: 'Hold on a minute, what are your principles?'

Geri, who had a lump removed from her breast as a teenager, continued: "So I had to question myself. That is the reason I left on that day - there was never a good day to leave."

Although the star quit last May, she said the split "is quite tender in my heart".

Her relationship with the other four girls was, she said, "like a marriage, I fell in love completely, passionately, I needed it".

However, Geri added: "Like one-in-three marriages, under the pressure of work schedules, the marriage broke up, it imploded."