Image caption Jordan Romero was due to do some school work during his trip

A 13-year-old American boy has become the youngest person to reach the summit of Mount Everest, his family says.

Jordan Romero, from California, telephoned his mother from the peak of the world's highest mountain, she said.

"Mom, I'm calling you from the top of the world," Leigh Anne Drake quoted her son as saying.

He was climbing with his father and three Sherpa guides. The previous record was held by a Nepalese boy of 16.

The 13-year-old has now conquered the highest mountains on six of the world's seven continents.

JORDAN'S SUMMITS Africa - Kilimanjaro: 2006

Europe - Elbrus: 2007

South America - Aconcagua: 2007

North America - Denali: 2008

Oceania - Carstensz Pyramid: 2009

Everest - Asia: 2010

He climbed Africa's Mount Kilimanjaro aged 10. He just needs to scale the Vinson Massif in Antarctica.

He has also scaled Mount Kosciuszko in Australia.

The team set off from Nepal's capital, Kathmandu, last month, heading for the base camp on the Chinese side of the mountain.

While Nepal insists that anyone planning to climb Mount Everest must be 16, China does not impose any age restrictions.

Some mountaineers have criticised the Romero family for letting him attempt the feat but his father said the ascent from the Chinese side is less dangerous, the AFP news agency reports.

Last month, his mother told the BBC he would do some school work during the trip.

Also on Saturday, Apa Sherpa, 50, climbed Everest for the 20th time, surpassing his own record.