Jessica Biel broke down in tears upon reaching the summit of Mount Kilimanjaro.

The American actress - who reached the top of Mount Kilimanjaro's 19,340-foot summit on Tuesday night (12.01.10) - was so emotional about completing the challenge for the 'Summit on the Summit: Kilimanjaro campaign' that she had to be consoled by UN Foundation executive Elizabeth Gore.

Speaking via satellite phone, Elizabeth said: "I walked over to Jessie and gave her a big hug. The two of us embraced and we just cried. Every single One Of Us was in absolute tears."

The 27-year-old star - who climbed the mountain with a team of celebrities, including actor Emile Hirsch and rapper Lupe Fiasco in order to raise awareness of the global water crisis - endured "zero temperatures" and "altitude sickness" on the gruelling trek.

Elizabeth told People magazine said: "We had a complete whiteout. There was so much snow, we could only see two or three feet in front of us. So we had to line up like a chain to make it to the final point. I'm so proud that every single one of us 12 climbers made it.

"The temperature was zero degrees and so many people were struggling. People had hurt limbs, people had altitude sickness."

Finally, after eight days of hiking, the group reached the town of Arusha in Tanzania yesterday (13.01.10).

Jessica will now join Elizabeth on a trip to a United Nations camp in Ethiopia to see some of the world's most significant water problems.