The celebrities taking part in this year’s Comic Relief 100km trek across the Kaisut Desert have already faced deadly snakes and falling rocks on day one.

Celebrities including Kara Tointon and Dermot O’Leary started their day with a trek over a 4,000ft-high hill and were immediately stopped by a rock slide which took half-an-hour to clear away.

The famous faces, including Craig David, Lorraine Kelly, former EastEnders star Nadia Sawalha and Strictly Come Dancing winner Kara, then had to give a wide berth to a deadly viper as temperatures hit 35C.

Radio 4 presenter Peter White, who is visually impaired, was given a helping hand by O’Leary during one part of the climb.

He said: “Dermot and I did a difficult bit of the climb together. I held onto his rucksack and tried not to drag him down. And this is only the first day.”

The team will cover 100 kilometres across the Kaisut Desert in northern Kenya in five days and face scorching temperatures of up to 40C.

They visited a sight clinic on the eve of the trek, where they met people from the local area who received treatment for cataracts and trachomas.

The BT Red Nose Desert Trek will raise money for Comic Relief projects which benefit deprived people across Africa and in the UK. A documentary about the trek will be broadcast on BBC1 in the run-up to Red Nose Day on March 18.

A Comic Relief spokeswoman said the team will be highlighting the issue of sight and the money they raise will prevent thousands of people in Africa from going blind or contracting eye conditions.

People can sponsor the team and get updates about the journey by visiting www.rednoseday.com/trek.