Laos plane crash
A Laos Airlines flight crashed in the Mekong River killing 49 (Reuters)

Forty-nine people, including some westerners, were killed in a plane crash in Laos.

A state-run Laos Airlines flight from the capital of Vientiane en route to Pakse, southern Laos, came down in the Mekong River as it was coming in to land.

Laos Ministry of Public Works and Transport, which operates the airline, said 44 passengers and five crew members were aboard.

Flight QV301 crashed in the waters of Southeast Asia longest river only 7-8 kilometres (4-5 miles) from Pakse airport.

"Upon preparing to land at Pakse Airport the aircraft ran into extreme bad weather conditions and was reportedly crashed into the Mekong River," the ministry said, adding there was no word of survivors.

"Lao airlines is taking all necessary steps to coordinate and dispatch all rescue units to the accident site in the hope of finding survivors and at the same time informing relatives of the passengers," the ministry said.

The airline said passengers included 17 Lao, seven French, five Australians, five Thais, three Koreans, two Vietnamese and one person each from Canada, China, Malaysia, Taiwan and the United States.

The plane, believed to be a French-Italian manufactured ATR-72 twin-engine turboprop, took off from Vientiane at 1445 local time (0745 GMT) and was supposed to complete the 467-kilometre (290-mile) route in an hour and ten minutes.

Laos Airlines expressed its condolences to the families of the victims in a statement.

The ministry said circumstances of the crash are being investigated.