Singer Kenna is already struggling with a celebrity charity climb up Africa's Mount Kilimanjaro, insisting the first day of the expedition was much harder than he expected.

The route we took was more difficult, with more rocks

The star joined Jessica Biel, Emile Hirsch and musicians Santigold and Lupe Fiasco on Thursday (07Jan10) as they began their trek to base camp ahead of their journey up the 19,340-foot (5,895-metre) peak in Tanzania, as part of a campaign to raise awareness of Africa's chronic water shortage.

Kenna, who previously attempted the feat in 2005 but failed, admits their first two-hour hike to base camp was excruciating.

He tells, "It was a bit harder than I expected. The route we took was more difficult, with more rocks. We had to cross a river a few times, and there were more ups and downs than the first time I did it".

But Kenna insists his tent mate, rapper Lupe Fiasco, is faring much better "He says he's a veteran. He went to sleep a lot later than me and trekked as much as I did and drank a lot of water and took some medication (for altitude sickness)".

The group of celebrity climbers begins its 50-mile (80.5-kilometre) journey up the mountain on Friday (08Jan10).

They'll be posting clips, photos and 'tweets' on the Summit website.