​Dam burst in Tibet (representative file photo)Kathmandu: Nepal’s rescue operations were temporarily halted for 90 minutes on Friday after a landslide-formed lake on the Nepal-China border began overflowing, triggering fears of another surge in the flood-ravaged region. The fresh alert came as a magnitude 5.1 earthquake struck China’s Sichuan province, adding to the mounting challenges facing the disaster-hit Himalayan region.Lake overflow triggers fresh flood alertA lake formed by debris from the massive glacier collapse began overflowing on Friday, raising fears of renewed flooding in communities already devastated by Wednesday’s flash floods.Nepal warned rescue teams to move to safer locations after authorities received information that the glacial lake had breached its banks. The Nepal Army subsequently suspended rescue operations for one hour and 30 minutes as authorities assessed the threat.Residents in Rasuwa district, near the border with China's Tibet, were seen rushing towards higher ground as the river level began rising, according to a Reuters witness."We can see that the level of water in the river is rising," Narendra Pariyar, the senior-most bureaucrat in Rasuwa district, said, adding that authorities were still assessing the situation.The rising water also prompted Chinese rescue personnel and vehicles to withdraw to a designated safe area, state broadcaster CCTV reported.Barrier lake holds millions of cubic metresThe lake was formed when debris from the glacier collapse blocked the river, creating a natural barrier and trapping water upstream.China mobilised an eight-member engineering team on Thursday to conduct aerial surveys and three-dimensional modelling of the lake. By Friday, the reservoir had grown to more than 2.5 million cubic metres, compared with an estimated 1.5 million to 2 million cubic metres a day earlier.Authorities fear that a breach could send another powerful surge downstream, threatening communities that are already struggling to recover from the earlier disaster.The latest crisis comes after a huge torrent of rock, ice, mud and debris tore through Himalayan river systems following the collapse on Wednesday.Death toll climbs as rescue efforts disruptedThe confirmed death toll in Nepal has risen to 469, while almost 1,000 people remain missing in Nepal and Tibet. At least 540 foreigners are among those reported missing.The floods swept through villages and valleys, destroying power stations, roads and bridges along a key route connecting Kathmandu with Lhasa in Tibet. The corridor is also popular with trekkers and pilgrims travelling towards Mount Kailash.Before the latest suspension, Nepalese rescue teams had been using helicopters to search for survivors and deliver emergency supplies to thousands of people cut off in towns and valleys. Emergency workers, including teams using sniffer dogs, had also recovered dozens of bodies swept downstream into the plains.Dibga Tamang was among the last people rescued from Rasuwa on Thursday, when he was airlifted with three others to an army camp in Nuwakot."All of our people have gone. They are dead," Tamang said. "I have no one left waiting for me. Everything and everyone is gone. The end."Nepal says it does not need foreign rescue teamsDespite offers of assistance from several countries, Nepal has said it does not currently require foreign search-and-rescue teams."The offer for help is natural. Our security agencies are doing the search and rescue operation. For now we don’t require such help,” Lok Bahadur Chhetri, spokesperson for the foreign ministry said on Friday.A South Korean rapid response team is already in Kathmandu but has not been deployed because Nepal has yet to establish a plan to accept foreign rescue teams, according to South Korea’s foreign ministry.China border crossing devastatedThe disaster has also caused extensive destruction around the Gyirong border crossing on the Chinese side. Chinese rescuers had yet to reach the worst-hit area as crews worked to clear debris from the access road.Dramatic footage from Wednesday showed torrents of muddy water and debris tearing through structures at the border crossing within seconds.CCTV reported that 558 people were missing in Tibet’s Gyirong County, including 260 foreign nationals. Three people have been confirmed dead on the Chinese side.Chinese Premier Li Qiang visited the disaster-hit area in Gyirong on Thursday as rescue and relief operations continued.Magnitude 5.1 earthquake hits ChinaAdding to the uncertainty in the region, a magnitude 5.1 earthquake struck Longchang City in Neijiang, Sichuan province, on Friday, according to the China Earthquake Networks Center.There were no immediate reports of casualties or damage from the earthquake.The fresh seismic event comes as authorities remain on alert across the Himalayan region, where rescue teams are already dealing with unstable terrain, blocked rivers and the risk of further landslides and flooding.Families wait for news of missingThe disaster has triggered a desperate search for missing relatives across several countries. Among those unaccounted for are dozens of Americans who had travelled from Nepal towards Tibet’s Mount Kailash.President Donald Trump said the United States had offered assistance to Nepal."Nobody's ever seen anything quite like that, where very powerful, strong, well-built buildings were wiped out like they were toothpicks. It's a terrible thing. We are sending aid and we've spoken to the leadership and we let them know anything they want, they'll have."