Cheryl Cole brake sdown in tears

Cheryl Cole broke down in tears on Mount Kilimanjaro yesterday (03.03.09).

The Girls Aloud star – who is taking part in the gruelling charity trek with eight other stars to raise money for Comic Relief – was left terrified after seeing a climber stretchered away suffering from potentially-fatal acute altitude sickness.

She sobbed: "He looked really scared. It shook us up.

"You feel strange at this altitude anyway. I started wondering if I was suffering too - but I'm alright and we've got each other to help us get through and hopefully get all the way to the top."

Although none of the celebrities taking part have suffered altitude sickness, they have been battling other health problems.

Radio presenter Chris Moyles has been stricken by vertigo, while fellow Radio 1 star Fearne Cotton has been plagued by nose bleeds as she grows accustomed to the high altitude.

Take That singer Gary Barlow is battling with a back injury he incurred before the treacherous climb began.

He said: "I woke up with bad back this morning. The rest of the guys did a big acclimatisation climb, but I gave my back a rest and went with a guide on my own for a lonely four-hour trek. It was the right thing to do though - I'm feeling better tonight - big day tomorrow."

Earlier on in the day, the celebrity climbers surprised Boyzone singer Ronan Keating – who turned 32 yesterday - by rousing him from his tent with a birthday singsong, balloons and cards from his family and friends. He was later presented with a huge birthday cake when the group set up camp for the night.

The other celebrities taking part on the nine-day trek up the world's largest free standing mountain are Cheryl's bandmate Kimberley Walsh, singer Alesha Dixon, and presenters Denise Van Outen and Ben Shephard.