Six Australians were killed when a Lao plane crashed into the Mekong River on Wednesday as it was coming into land in bad weather in southern Laos, the Department of Foreign Affairs and Trade (DFAT) confirmed on Thursday.

A DFAT spokeswoman said Australian consular officials were in contact with the victims' families, providing consular support.

"Australian consular officials are traveling to Pakse today," the spokeswoman said in a statement on Thursday. "We expect the recovery and identification efforts will recommence at first light. This may take some time."

According to local media, all 44 passengers and five crew were killed. A Sydney family of four, Gavin Rhodes and his families, including two young children, has already been confirmed as on board Lao Airlines flight QV301 from the Lao capital to Pakse on Wednesday.

The others are an Australian aid worker Michael Creighton and his father. Michael Creighton had been an operations manager at Norwegian People's Aid's mine action program, and had been in Laos for almost a year.

Lao officials said 44 passengers and five crew members were aboard flight QV301 from the Lao capital to Pakse.

"Upon preparing to land at Pakse Airport the aircraft ran into extreme bad weather conditions and reportedly crashed into the Mekong River," the Lao government said in a statement.

And an unconfirmed passenger list suggests that more than half of the people aboard were foreign nationals, including those from France, South Korea, the United States, China, Vietnam, Canada and Malaysia.