Fire and rescue personnel conduct search and rescue operations on a section of a road leading to Gyirong Port, which was damaged after a mudslide two days earlier, in Gyirong County, in China's western Tibet region, on Friday. (AFP via Yonhap) South Korean government and corporate response teams are struggling to reach a hydropower plant construction site in Nepal where nine South Koreans remain unaccounted for amid concerns over further flooding, officials said Friday.The government's joint rapid response team arrived in Kathmandu late Thursday, while corporate response teams from Doosan Enerbility Co. and Korea South-East Power Co. arrived early Friday.The government and the companies have secured a total of six helicopters for search and rescue operations, but the aircraft have yet to receive flight approval from Nepalese authorities, according to ministry officials."Helicopter travel is essential to reach the area, as roads and bridges have been washed away. But Nepalese authorities have restricted private helicopter operations over concerns about the possibility of additional flooding," a ministry oficial said.The nine missing people -- six employees of Doosan and three of the power generation firm -- were working at a construction site in Rasuwa district when a massive flash flood and mudslide struck the area Wednesday morning.They had been staying in offices and accommodations in a relatively low-lying area, many of which are believed to have been swept away by the flooding.Families of the missing workers urged the government to quickly send helicopters to the site, saying nearly 48 hours had passed since the disaster."Our only request is to get the helicopters flying as soon as possible," family members said at a press briefing Friday. "We believe today is the golden time. Please send the helicopters."Separately, nine of 10 other Doosan workers who had been isolated in a different area were transported by Nepalese military helicopters to a safer area Thursday.They had initially been expected to travel to Kathmandu Friday, though travel plans have yet to be confirmed due to the local conditions.The remaining worker, a Doosan site manager, has stayed at the construction site with local employees, saying he would remain until they were evacuated, officials said.The disaster in Nepal's north-central Himalayan region near the Nepal-Tibet border has killed nearly 500 people and left more than 1,500 others unaccounted for, according to foreign media reports.Nepal's disaster authorities warned that water levels in a newly formed lake upstream were rising as debris from the floods blocked the river, raising concerns that the blockage could collapse.They urged residents in downstream areas and rescue workers to stay away from riverbanks and other high-risk areas, media reports said.Meanwhile, the South Korean government is considering sending an overseas emergency relief team to provide additional search and rescue support. Seoul has notified Nepal of its intention to dispatch the team and is discussing the matter with Nepalese authorities.The defense ministry has decided to support the operation with a KC-330 Cygnus multirole tanker transport aircraft to carry relief equipment and supplies, with details being coordinated with the foreign ministry, officials said. (Yonhap)