PRAID, Romania (Reuters) -Severe floods in Romania are threatening to destroy the Praid salt mine, one of Europe's largest salt reserves which attracts half a million tourists each year with its spectacular galleries housing an adventure park and chapel carved in salt.

Authorities have shut down the mine as the worst floods in 30 years in the central Romanian county of Harghita have swollen a nearby stream, further flooding part of the mine.

The floods are threatening to destroy the livelihood of people in the town of Praid who have relied on tourism centred around the salt mine for decades, local authority officials said.

"A problem with the salt mine can have catastrophic consequences for the entire region," said Csongor Zsombori, head accountant at the Praid branch of the state-controlled National Salt Company S.A. which partly owns the mine.

While part of the mine has been producing salt, with an annual production capacity of around 70,000-100,000 metric tons, its huge galleries which also house a medical centre, receive tourists, including for medical treatment for respiratory diseases.

Laszlo Nyagrus, mayor of Praid, said the miners have removed their equipment and machines and were working to preserve another part of the mine which has not been open to visitors so far.

"They are trying to save this area, these galleries, by building so-called sluices and dams to protect it, so that at least this part ... will not be damaged," he said.

"We need to look at what can be done very quickly in the tourism sector, what opportunities can be explored or should be explored, so that we can retain as many tourists as possible in Praid."

(Reporting by Emoke Kerekes;Writing by Krisztina Than; Editing by Emelia Sithole-Matarise)