Thai Navy and Air Force officers said in Bangkok on Friday that weather, poor visibility in the muddy river and strong currents in the Mekong were posing a problem for Thai scuba divers assisting recovery operations.
Gp Capt Manop Mussu, the deputy director of the Air Force's public relations division, said the search for the plane was difficult given the size of the Mekong and its strong currents. He added that the plane could be struck in the muddy riverbed, making it more difficult to find.
The Navy has dispatched 14 officers to the crash site, including nine scuba divers, while the Air Force sent another nine officers to help locate the victims and the plane.
They are among around 100 Thai rescue workers from private and public units sent to the crash site along with workers from Laos, France and Singapore.
Flight QV301 crashed near Pakse airport on Wednesday with 44 passengers, including five Thais, and five crew members on board. All are presumed dead.
A Thai forensics team led by Pol Gen Jarumporn Suramanee, an advisor to the police force and expert in forensic science and body identification, was meanwhile sent to the southern Lao town on Friday.
They brought with them information to help identify the missing Thais, including fingerprint examples from the Provincial Administration Department. They are also carrying passenger details on the Australian victims from the crash. National police chief Pol Gen Adul Saengsingkaew said that Australia had requested the Thai police examine the bodies of its nationals.
As of Friday morning only 17 bodies had been found, according to Lao Public Works and Transport Minister Sommad Pholsena. Relatives of a Chinese victim identified their family member on Friday, marking the first identification of a body since the crash.
Exasperated officials in Laos said they lack the equipment and manpower to locate the fuselage and more than 30 bodies still unaccounted for two days after the crash.
Divers said they lacked sonar and other equipment for finding the black box and fuselage of the ATR-72 aircraft, which is believed to have crashed on the riverbank before skidding into the water and sinking.
"It's very difficult to find (bodies) under water," the openly frustrated transport minister told reporters at the crash site, where the rescue operation awaited the arrival of more help. "If we could find (the plane), we would have found it already."
"We think the plane broke into two pieces. The tail of the plane contains the black box," Transport Minister Chadchart Sittipunt said in a telephone interview after meeting with his Lao counterpart in Pakse. "It is believed that many bodies of the passengers are still stuck in the plane, or else they would have surfaced on the river."
France's accident investigation agency said in a statement that it was sending four investigators to help Laos with the probe into the cause of the crash. The statement said the team would work with technical advisers from ATR, the French-Italian manufacturer of the aircraft, which has said it delivered the plane to Lao Airlines in March.
Lao Airlines said the plane from Vientiane ran into extremely bad weather as it prepared to land at Pakse airport on Wednesday. No further details on the investigation or circumstances of the crash have been released. The crash occurred about 7 kilometres from the airport.
Passengers included 16 Lao nationals, seven French, six Australians, three Koreans, three Vietnamese and one person each from China, Malaysia, Taiwan and the United States. A person who had been listed as a Canadian was instead added to the list of Vietnamese.
The passengers included foreign tourists and expatriates working in Laos.