A Sydney family of four including two young children is among six Australians feared dead after a plane crashed into the Mekong River as it was coming into land in bad weather in southern Laos.

The Lao Airlines flight crashed on Wednesday, apparently killing all on board, including passengers from 11 countries, the Lao government says.

The Australian victims are reported to be from two families – a tax consultant from Sydney, his wife and their son and daughter, as well as an aid worker and his son.

The state-owned airline says no survivors had been found among the 49 passengers, most of whom were foreigners, and five crew members but the river was being searched.

Lao Airlines says the aircraft hit “extreme” bad weather and had crashed into the Mekong about 4pm on Wednesday local time (8pm AEDT).

“There were no news of survivors at this time,” the airline said. It did not confirm the number of deaths.

The state-run Laos news agency KPL also said everyone on board was believed to have perished, as did a Thai foreign ministry spokesman who had slightly different numbers for those aboard.

A Sydney family of four including two young children is among six Australians feared dead after a plane crashed into the Mekong River as it was coming into land in bad weather in southern Laos.

In a statement issued from the email of Sydney’s Etlanda Taxation and accounting services, the Rhodes family asked all members of the press to “respect their privacy at this difficult time”.

“We will not be providing comment or information. Any interview requests will be declined,” the brief statement reads.

The statement includes a photograph of Gavin Rhodes, 39, Phoumalaysy (Lea) Rhodes, 35, with their children 17-month-old Manfred Rhodes and three-year-old Jadesuda Rhodes.

Seven French citizens and five Thais were among those thought to have died when the turboprop ATR-72 came down around 8km from Pakse airport in Champasak province.

The Department of Foreign Affairs in Canberra says the Australian embassy has been told not to expect any survivors.

“Lao authorities have told our embassy in Vientiane they do not expect any survivors.”

Local news agency KPL says eyewitnesses said wild winds had affected the plane.

“It stopped and then it appeared to be blown away by strong winds. Nobody knew where it had gone,” said an unnamed local resident.

“The plane was completely submerged in water.”

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 local time 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 airline expressed its “condolences” to relatives of the passengers.

Authorities are investigating the crash.