All passengers onboard - 44 passengers and five crews - were killed when Lao Airlines crashed into Mekong River in Laos at 2:45 pm (Laos), 6:45 pm AEDT.

Among those dead were six Australians - A Sydney tax consultant, his wife, son and daughter; an aid worker and his son - whose identities were withdrawn upon their relatives' request.

The information was already confirmed by a ministry spokesman from the Department of Foreign Affairs and Trade.

"We understand there were six Australians listed as boarding a Lao Airlines flight from Vientiane to Pakse that crashed approximately eight kilometres from Pakse, Laos, on Wednesday 16 October 2013.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.''

Lao Ailrines had already expressed its condolences to the families of the passengers and had announced that it is doing all the 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."

Lao Airlines stated that the crash was due to "extreme" weather condition.

Witnesses told what they saw of the dismal accident.

"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," one witness told local reporters.

The rescue centre set up in a Pakse temple was in "absolute horror" said another witness.

"I saw lifeless bodies laying about and other lifeless bodies being brought in, some connected to IV drips."

In a passenger list published by local media in Thailand, it stated that more than half of the passengers onboard were foreign nationals from Australia, South Korea, United States, China, Taiwan, Vietnam, Canada and Malaysia. The passengers list was obtained by local media from Lao Airlines.

Laos Airlines was founded in 1976 and had been flying tourists in China, Thailand, Cambodia and Vietnam.

Under its previous name Laos Aviation, Laos Airlines was involved to previous plane crash in October 2000 in a remote mountainous region in Laos.