Search and rescue operations are continuing in Nepal after severe flooding in Nepal and China caused mud and debris to fill tunnels at hydropower plants, where hundreds of workers are believed to be trapped.

The Independent Power Producers' Association of Nepal (IPPAN), which represents hydropower companies in the country, said at least 900 workers were missing at 12 hydropower projects damaged by floods in Nepal's Rasuwa and Nuwakot districts.

IPPAN Chairman Mohan Kumar Dangi said around 500 of the missing workers were believed to be trapped inside power plant tunnels.

Different figures reported for missing workers

While authorities have given different figures regarding the number of missing workers, several foreign teams have also joined search and rescue efforts in Nepal.

Jakob Steiner, a geoscientist at Austria's University of Graz, said tunnels used at hydropower facilities are generally wide enough for people to take shelter.

Steiner explained that the tunnels are built to provide access to hydropower infrastructure and divert water for electricity generation, adding that some tunnels are large enough for trucks to pass through.

He said oxygen may have been delivered to some of the trapped workers and stressed that rescue teams were continuing their efforts, but were racing against time.

Steiner also warned that those trapped inside the tunnels would need food and water, adding that the chances of finding survivors decrease as time passes.

Workers reported asking for help

IPPAN Chairman Dangi said some workers contacted their colleagues and requested help when the disaster struck last Wednesday.

Dangi said some workers who managed to escape from the tunnels had also contacted authorities and their relatives, but many others were still believed to be trapped underground.

As six days have passed since the disaster, concerns have grown that some of the trapped workers may have died due to a lack of oxygen.

Nepal Army continues rescue efforts

Nepal Army spokesperson Brigadier General Raja Ram Basnet said rescue teams were continuing operations to reach people trapped in mountainous areas, settlements and river regions.

The search efforts are being carried out as authorities race against time to determine the fate of hundreds of workers believed to be inside flood-damaged hydropower tunnels. (ILKHA)