Rescuers searched for bodies Thursday after a Lao Airlines plane carrying dozens of people, about half of them foreigners, crashed in the Mekong River with everybody on board believed dead.

Seven French citizens, six Australians and five Thais were among those thought to have been killed when the turboprop ATR-72 came down on Wednesday near Pakse airport in Champasak province.

"The search and rescue is still going on in Pakse," Thai foreign ministry spokesman Sek Wannamethee told AFP.

"The search teams in Laos are taking the bodies to a local hospital."

Citizens from some 10 countries were reported to have been on the flight from the capital Vientiane.

The state-run Laos news agency KPL said all 49 passengers were believed to have perished.

"The plane was about to land but appeared to be hit by a strong wind, causing its head to ascend and pushing it away from the airport area and out of reach of the air traffic control radar," it quoted a witness as saying.

State-owned Lao Airlines said the aircraft hit "extreme" bad weather and had crashed into the Mekong with "no news of survivors at this time".

It gave a slightly different figure of 44 passengers and five crew and did not confirm the number of deaths.

France said it was rushing embassy officials to the site of the crash in Pakse, which is a hub for tourists travelling to more remote areas in southern Laos.

French President Francois Hollande learned of the disaster "with profound emotion and great sadness" and offered "sincere condolences" and full support to the victims' families, his office said in a statement.

According to a passenger list published by Thai media, more than half of the people onboard were foreign nationals.

They also included people from the United States, Vietnam, Canada and Malaysia, according to the document, which media said they obtained from the airline.

The US Embassy's Press Attache in Malaysia, Harvey Sernovitz said, "At this time, we can confirm that one U.S. citizen was on board. Officials from the U.S. Embassy in Vientiane are in contact with the individual’s family. Out of respect for them, we are not providing additional information at this time.”

Australia meanwhile said six of its nationals were feared dead, including a family of four.

"Australian consular officials are in contact with the families of those thought to be on the flight. Lao authorities have told our embassy in Vientiane they do not expect any survivors," a foreign ministry spokesperson said, adding that recovery and identification "may take some time".

Thailand said five of its nationals had died.

Three South Koreans were also among the victims, according to the Transport Ministry in Seoul.

Taiwan said one of its citizens was killed while Beijing's official Xinhua news agency said one Chinese was on board. It said an earlier figure of two had included the Taiwanese victim.

The airline expressed its "condolences" to relatives of the passengers.

"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," it said in a statement.

'Absolute horror'

Witnesses reported horrendous scenes at an emergency centre set up in a temple in Pakse.

"I saw lifeless bodies laying about and other lifeless bodies being brought in, some connected to IV drips," a foreign resident told the Bangkok Post.

"It's absolute horror."

The QV301 flight set off from Vientiane on time at 2.45pm (0745 GMT) and was supposed to arrive in Pakse just over an hour later.

French-Italian aircraft manufacturer ATR said the twin-engine turboprop aircraft was new and had been delivered in March.

The director general of the country's Department of Civil Aviation, Yakua Lopangkao, told the Vientiane Times newspaper that the accident may have occurred due to bad weather triggered by tropical storm Nari.

Local officials helped to pull bodies from the aircraft and bring them ashore after the plane sank below the surface of the Mekong, it reported.

Founded in 1976, Lao Airlines serves domestic airports and destinations in China, Thailand, Cambodia and Vietnam.

Impoverished Laos, a one-party communist state, has had 29 fatal air accidents since the 1950s, according to the Aviation Safety Network, whose data showed that the country's safety record had improved dramatically in the last decade.

The last fatal air accident was in October 2000 when eight people died after a plane operated by the airline -- then called Lao Aviation -- crashed in remote mountains in the northeast of the country.