A 13-year-old American boy on Saturday became the youngest person to conquer Mount Everest, his website said, setting a new but controversial world record.

Jordan Romero was one of more than 50 mountaineers who reached the top of the world’s highest peak early on Saturday, among them Apa Sherpa, who broke his own world record by summiting for the 20th time. The 13-year-old from Big Bear, California was “unbelievably happy” when he called in from the summit via satellite phone, said a statement on his website, http://www.jordanromero.com.

“The team just called in and confirmed that they are standing on top of Mount Everest — the highest peak in the world. Their dreams have now come true,” it said.

“Everyone sounded unbelievably happy. They also thanked everyone who supported them and encouraged them throughout their journey.” Jordan is three years younger than the previous record holder, believed to be Temba Tsheri of Nepal who reached the peak at age 16.

The Californian’s successful climb brought him a step closer to achieving his ultimate goal — set when he saw a mural at school aged just nine — of becoming the youngest person to climb the highest peaks on all seven continents. He now has only the Vinson Massif in Antarctica to climb.

Scores of supporters posted congratulations on his website, but the expedition has also attracted criticism from mountaineers, some of whom said Jordan was too young to undertake such a dangerous climb.

Hundreds of people have died trying to climb Mount Everest, many succumbing to altitude sickness or accidents, and the route that Jordan and his father and stepmother took is notorious for avalanches and high winds.