A mass grave containing 17.5 tonnes of human ashes has been unearthed in northern Poland, close to the former Nazi concentration camp of Soldau.

Tomasz Jankowski from Poland's national remembrance institute said the grave contained at least 8,000 victims.

The bodies are thought to have been dug up and burned in a Nazi operation to hide traces of their murders.

The Nazis murdered Jews, political opponents and members of the Polish elite at Soldau.

The concentration camp was built in 1939 for transit, internment and extermination and used throughout the Nazi occupation.

Up to 30,000 people are thought to have been killed there and researchers hope to carry out DNA analysis of the remains to find out more about the victims. Among the Poles who were murdered were members of the clergy and intelligentsia.

Archaeologists have found hundreds of traces of clothing, buttons and other items, but nothing of value, indicating the bodies were robbed before being set alight.

Mr Jankowski said two pits had been found near Soldau, now known as Dzialdowo, and further excavation would take place to search for more. The estimate of 8,000 victims is based on a person's body weight estimated at 2kg.

In a separate development, Polish Prime Minister Mateusz Morawiecki said on Wednesday that a report had been prepared detailing not only Nazi war crimes, but also calculations of financial losses that had been converted into current values.

He said Germany had caused immense harm to the Polish people and had never paid reparations. Germany has said the issue of reparations was legally closed in the 1950s.

Some six million Poles died in the war, including three million Jews. An MP in Poland's nationalist-conservative government said in 2019 that losses could amount to $850bn (£715bn). (BBC)