KATHMANDU - Nepal's aviation ministry said Saturday that pilot error was the likely cause of a plane crash that killed all 19 on board, including seven British and five Chinese trekkers bound for Mount Everest.

The twin-propeller Sita Air plane had just taken off on Friday from Kathmandu and was headed to the town of Lukla, gateway to Mount Everest, when it plunged into the banks of a river near the city's airport around daybreak.

"The pilot's failure to maintain the required radius is a likely cause of the accident," said ministry official Suresh Acharya, adding that the plane turned too sharply because it had not gained enough altitude.

The airport said on Friday the plane's right engine burst into flames after being hit by a large bird, and slammed into a river bank moments later, exploding into a huge fireball.

Acharya said the accident occurred after the pilot made a steep, narrow turn to get back to the airport following the bird strike without attaining sufficient altitude.

"A plane crash does not occur simply just because its engine was hit by a bird," he said.

The victims had all arrived in Nepal on Wednesday.

They were due to begin a trek towards Everest Base Camp on Saturday on an expedition scheduled to last until mid-October with English firm Explore Worldwide, using local guides from Sherpa Adventures.