Authorities in Denmark are working against the clock to stop a slow-moving landslide of contaminated soil from reaching a nearby water source, as public officials and the company that operated the site argue over who should pay for the massive clean-up.

The 250ft-tall mountain of dirt at the Nordic Waste reprocessing plant south of the town of Randers in north-western Denmark contains some 100 million cubic feet of soil contaminated with heavy metals and oil products.

It is moving at a pace of up to 16 inches per hour towards a stream connected to the Baltic Sea via the Randers Fjord.

The landslide started on December 10.

Nine days later, Nordic Waste gave up trying to get it under control, leaving the task up to Randers council, which has been re-routing the stream by laying pipes, allowing it to pass the site safely.

Environment minister Magnus Heunicke said on Friday that authorities are extending those pipes and that a sheet pile wall is being constructed, along with several basins for the contaminated water.

Water from rain and melting snow are the biggest problems, Mr Heunicke said. In the past week, western Denmark has seen huge amounts of snow and rain.

“It’s about separating the polluted water from the clean water,” he told a news conference, adding that the work is “enormously difficult.”

On Monday, a report by the Geological Survey of Denmark and Greenland, or GEUS, said the continuous deposit of soil on top of a sloping clay pit at Nordic Waste was the main cause for the landslide.

GEUS added that there had been landslides in the region since 2021.

United Shipping and Trading Company, or USTC, which is behind Nordic Waste, earlier blamed the landslide on climatic conditions beyond its control.

The area “has been exposed to enormous amounts of rain, as 2023 has been the wettest year ever in Denmark. This has resulted in a natural disaster of a calibre never before seen in Denmark”, it said.

It is still unclear who will have to pay for the clean-up.

Nordic Waste was declared bankrupt earlier this week after the Danish Environmental Protection Agency ordered it to provide security of more than 200 million kroner (£23 million) to prevent an environmental disaster.

Danish Prime Minister Mette Frederiksen, who visited the site on Monday, said it would be unfair if Danish taxpayers had to pay.

Nina Ostergaard Borris, Nordic Waste’s chief executive, said it would take up five years to restore the site and it could potentially cost billions of kroner.

She said the situation “is far more serious than anyone could have imagined, and the task of saving the area is far greater than what Nordic Waste or USTC can handle”.

The case has started a debate about whether Nordic Waste has a moral responsibility to pay.

The government has criticised Denmark’s sixth-richest man, Torben Ostergaard-Nielsen, who is behind USTC, for not paying.