VIENTIANE, Aug. 9 (Xinhua) -- Lao authorities have been speeding up the search, relief and recovery efforts after the flash flood in Attapeu province, where around 100 people are still missing, local daily Vientiane Times reported on Thursday.

Lao Deputy Prime Minister Sonexay Siphandone said that locating the missing people remains a matter of urgency as many foreign rescue teams have returned home.

As of Wednesday, the death toll from the July 23 inundation caused by the collapse of an auxiliary dam at the Xe-Pian Xe-Namnoy hydropower project in Attapeu, some 560 km southeast of Lao capital Vientiane, had climbed to 35.

Among the 35, three died in hospital, Sonexay on Wednesday told a meeting of the National Ad Hoc Committee in charge of dealing with the aftermath of the flood.

A local official involved in victim assistance said hope was fading for those who were still missing. Many of them were children and old people, who witnesses said had been swept away by the raging torrent. Rescue efforts have been hampered by difficult conditions as they wade through deep, sticky mud. And with many of those missing thought to be buried in the mud, heat-detecting devices are unlikely to function, said the daily.

Unexploded ordnance (UXO) dropped by the United States during the Vietnam War that is reportedly still buried in the flooded area is an added difficulty in the search and rescue effort.

The deputy prime minister told officials to properly distribute relief supplies to meet the needs of all affected villagers.

The Lao Ministry of Public Works and Transport was told to expedite construction of four bridges and improve roads to ease access between the provincial capital and Sanmaxay district and accelerate the transport of supplies to temporary shelters.

More than 6,000 displaced people are now living in five temporary centers, including five schools.

Sonexay called for hard work to speed up the construction of temporary houses to accommodate those currently living in schools. This would enable the schools to reopen for the start of the new academic year, which begins next month.

The committee noted that the most urgent need was for dried and instant food and rice, along with drinking water and clean water for daily use, as well as household and cooking equipment.

The official stressed the need to ensure the supplies and money that had been donated was used efficiently for the intended purposes, and in a transparent manner.

On July 23, a saddle dam of the Xe-Pian Xe-Namnoy hydroelectric power project, invested by South Korean, Thai and Lao companies, burst, unleashing flood water from the mountain to 13 villages of Sanamxay district downstream the Xe Pian River.

Six villages were almost submerged by the muddy flood with 13,000 villagers being affected. Till Wednesday, 35 people have been confirmed dead and 96 others remain missing in the dam collapse accident.