The Jump: Ex-Girls Aloud star Sarah Harding leaves show

Former Girls Aloud singer Sarah Harding has become the sixth contestant to drop out of Channel 4 series The Jump because of injury.

The 34-year-old said she had "no choice" but to leave the reality skiing show because of a ligament injury.

Olympic gymnast Beth Tweddle, actress Tina Hobley and Olympic swimmer Rebecca Adlington have already pulled out.

Harding, whose departure will be aired on Sunday, said she was thankful for the "once-in-a-lifetime journey".

The Jump sees celebrities taking part in various winter sports competitions, including ski-jumping, bobsleigh and speed skating in Austria.

The show's third series has now seen six stars retire from the slopes.

• Britain's most successful gymnast Tweddle, 30, needed neck surgery following a fall during training

• Former Olympic swimming champion Rebecca Adlington, 26, withdrew after dislocating her shoulder

• Holby City actress Hobley, 44, also headed for the exit after she dislocated her elbow and suffered two fractures to her arm

• Made In Chelsea star Mark-Francis Vandelli, 26, pulled out after fracturing his ankle

• 1992 Olympic 100m champion Linford Christie pulled out after he failed to recover in time from a hamstring injury

After revealing her injury, Harding tweeted that she had been "gutted" to receive the news that after six weeks of training she would not be able to continue.

But she said to make it as far as she did had surpassed her own expectations.

'Great competitor'

A spokeswoman for Channel 4 confirmed Harding had withdrawn on medical advice after pulling a ligament in her knee during training on Friday.

"She has been advised by medics to rest and will undergo physiotherapy. Sarah has been a great competitor and we wish her a speedy recovery," she said.

Beth Tweddle tweeted a picture of herself wearing a neck brace before leaving hospital

Former England rugby player Ben Cohen, 37, who was drafted in as some of the stars were forced to drop out, was also injured after he said he had used his face to stop himself in an accident.

He lost two teeth and needed 20 stitches, he said on Twitter, but will remain in the competition.

At the beginning of February, Channel 4 said it had asked producers to "review safety procedures again to further reduce the prospect of accident".

The first review came after Olympic bronze medallist Tweddle had surgery to fuse fractured vertebrae in her neck. She was discharged from hospital 10 days later.