An NHS psychiatrist is among 33 British nationals unaccounted for in Nepal following a devastating flash flood that tore through the region on Wednesday. The catastrophic floods, triggered by a glacier collapse, have killed at least 538 people and left more than 1,500 missing in Nepal and Tibet.

Desperate families of those visiting the mountainous region have now flown to Nepal in a bid to find their loved ones. Among them is Manjula Atmakur, wife of 54-year-old Pravin Atmakur, a consultant psychiatrist who was leading a group of 77 pilgrims to Mount Kailash in Tibet when the disaster struck. Mrs. Atmakur arrived in Kathmandu on Friday morning and has begun her search.

"I am emotionally broken. I don't know how my husband is. In which situation. I want him back," Mrs. Atmakur told reporters, adding, "I came here with the only agenda that I want to take Pravin back home alive."

She last spoke to her husband on August 15, and believes he was returning from Tibet into Nepal when the floods hit. The floods were unleashed by a glacier collapse, sending torrents of water and mud crashing through villages and tourist areas. Footage showed the mudslide racing down the Trishuli River valley and through Gyirong Port, a major border crossing between Nepal and Tibet.

Another family of four from Surrey, including former Mrs. India UK Surabhi Sahu, 44, her husband Santosh, 46, and their children Spandan, 18, and Syna, 13, are also among the missing Britons. The family had been on an adventure trek across the Nepal-China border and were due to return in ten days.

Nelly Chhetri, 18, and her mother Yashika Basnet, 56, an NHS worker, have also not been heard from since joining a tour group for a pilgrimage. Their family has reported no contact from the UK Foreign Office.

Samitra Sapkota, 25, the wife of British man Pramod Poudel, is also missing. Mr. Poudel, who runs a Nepalese street food company in Sussex, last spoke to his wife the morning of the flood. "I have seen pictures of where my hometown used to be, where my family used to live - my mum, my dad, my brother, my wife...there's nothing there," he stated.

Sunil Amin described the "horrible, horrible feeling" of repeatedly trying to contact his wife, Hema Amin, 63, who was on a pilgrimage with her sister. Sarada Simkhada, 55, a senior nurse at Darent Valley Hospital, was also on a pilgrimage. Her relatives last had contact when she was at the Kailash Hotel in Timure on the Nepal-China border.

Foreign Office minister Stephen Doughty confirmed the figure of 33 Britons missing, but noted that the number "may fluctuate." He stated that UK teams in Kathmandu and Beijing are in close contact with families and that support is being provided to those who travel to the region. "This is a very, very complex situation, very remote areas, and you'll have seen the scale of the devastation," Doughty said.

Scientists believe the flooding was caused by a huge chunk of a glacier breaking off and temporarily damming a river, leading to a surge of water downstream. The US Geological Survey reported a magnitude 5.2 glacier collapse that resulted in the catastrophic debris flow. Rescuers continue to search for the thousands missing, while authorities warn of further flooding from a newly formed lake upstream that is already overflowing.