There is no evidence that a Nazi train rumoured to be carrying gems and gold has been found in Poland, experts say.

Researchers presenting findings about the alleged discovery in the Polish town of Walbrzych said there might be a tunnel but no train.

However, one of those who claimed to have discovered the train said he still believed it was there.

It was claimed that the train was hidden underground near Wroclaw as Soviet forces approached in 1945.

The Nazis had many miles of tunnels constructed near Walbrzych during World War Two.

In August, Deputy Culture Minister Piotr Zuchowski said that ground-penetrating radar images had left him "99% convinced" that a German military train was buried near Walbrzych.

He said images appeared to show a train equipped with gun turrets.

But on Tuesday, Professor Janusz Madej from Krakow's Academy of Mining said its geological survey of the site had found no evidence of a train.

"There may be a tunnel. There is no train," he told a press conference in Walbrzych.

Local folklore said an armoured train had been carrying gold from what is now the Polish city of Wroclaw as the Soviet army closed in at the end of World War Two.

It was said to have gone missing near Ksiaz castle, 3km (two miles) from Walbrzych.

Earlier this year, Piotr Koper, from Poland, and Andreas Richter, from Germany, told authorities that they knew the location of the train.

Through lawyers, they said that they wanted 10% of the value of anything that was found.

At the news conference on Tuesday,  Koper questioned the survey methodology and said he still believed the train was there.

Information about the train's location was reported to have come in a deathbed confession from a person who claimed they had helped to conceal it.

Between 1943 and 1945, the Nazis forced prisoners of war to dig more than 9km of tunnels near Walbrzych that were apparently to be used as factories. Some are now tourist attractions.