Preliminary investigations have pointed to a collapsed glacier as the cause of the flash flood on the Nepal-Tibet border, highlighting the issue of rapidly melting Himalayan ice, scientists have told the BBC.

Initial reports of an earthquake led many to believe that a tremor had caused a landslide, which in turn caused the flood that has killed at least 177 people.

However, the US Geological Survey then clarified that the disaster was caused by a "glacial collapse", which is when a glacier or part of a glacier disintegrates.

The impact of the collapsed glacier hitting the bottom of a valley was so powerful that it registered a magnitude of 5.2, according to USGS data and scientists who have analysed the event.

Dr Simon Cook, a glacier expert with the University of Dundee, told the BBC his team had detected that the lower part of a glacier in Nepal near the Langtang Lirung peak - which is approximately 15km (9 miles) west of the site of the floods - had collapsed.

He estimated that the glacier collapsed in a northwesterly direction and then travelled westwards downstream.

The death toll from Wednesday’s flash floods has reached 289, with hundreds of others, including foreign tourists, still out of contact as of 1:30pm on Thursday, police said.