A small plane carrying 21 people including two foreigners has gone missing in west Nepal, an airport official said on Wednesday.

The Twin Otter aircraft, operated by Tara Air, was carrying 18 passengers and a crew of three on a flight from Pokhara, 125 km (80 miles) west of Kathmandu, to Jomsom when it lost contact with the control tower.

"Two helicopters are on a search-and-rescue mission," Pokhara airport official Yogendra Kunwar said. "There is no trace of the aircraft so far."