An early flood warning system designed to save the lives of thousands of people in the Everest region may no longer be working, Nepalese officials have admitted to the BBC, after it was allowed to fall into a state of disrepair.

The disclosure came after villagers in the local Sherpa communities told the BBC no inspection of the UN-supported project had been carried out for many years after the dangerous Imja glacial lake was last drained in 2016.

Since then, no maintenance has been undertaken, which means siren towers have been left to rust, while some have even had their batteries stolen, according to locals.

On top of this, the satellite data reception transmitting the lake's water level - which can then be used to send out mobile phone alerts to locals - has been unreliable, officials at Nepal's department of hydrology and meteorology (DHM) told the BBC.

The Imja lake, which sits at a little over 5,000m (16,400ft) above sea level, has not burst since it was drained a decade ago - at which point, it was almost 150m deep in places.

Back then, the depth of the lake was reduced by about 3.5m as part of a $3.5m risk reduction project, which included the early warning system.

But scientists warn global warming-induced fast melting glaciers are causing many Himalayan glacial lakes to expand dangerously - meaning they can then burst out and sweep away downstream settlements, trekking routes and bridges.

Ice loss rates have doubled in the Hindu Khush Himalaya region since 2000, according to a recent assessment by the Kathmandu-based International Centre for Integrated Mountain Development.

In the Everest region alone, there have been at least five floods from glacial lakes in the last five decades, leaving those living in Imja lake's path fearing for the future.

Going by the state of the siren towers, we don't expect to get any flood warning from them even when Imja lake bursts, said Ang Nuru Sherpa, chairman of the Chaurikharka buffer zone area adjoining the Sagarmatha national park in the Everest region.

The siren tower in our village is rusting and leaning and is set to fall any time because there has never been any maintenance.

It is not that officials are not aware of the risks. Niraj Pradhananga, a senior meteorologist in the DHM, said central government had failed to allocate any budget, while suggestions the maintenance cost could be covered by hydro-power providers further down the valley have not come to fruition.

Archana Shrestha, the DHM's acting director general, acknowledged funds had been redirected to upgrade the early warning system for another glacial lake.

However, local leaders and residents, including Tshering Sherpa, chief executive officer of the Sagarmatha Pollution Control Committee, expressed frustration over the lack of preventive measures, as both local communities and trekkers are vulnerable to potential floods.

In the context of global warming and its impact on glacier dynamics, the need for an effective monitoring and alerting system has never been more critical for the people residing in the Everest region.