At least three people died and six were injured when a helicopter crashed near the Mount Everest base camp in Nepal on Wednesday, an army officer said.

The Russian-built MI-17, owned by private Simrik Airlines, was carrying nine people, including a crew of four, to the camp when it crashed. The three people killed were from Nepal.

More than 1,000 people are at the base camp, part of more than 20 expeditions trying to climb the world's highest mountain, 8,850 metres (29,035 feet), for Thursday's 50th anniversary of the first ascent.