Naturists in a German seaside resort have scored a major victory after local authorities issued new rules to force sunbathers to strip off on nudist beaches.

Germany has a coastline extending over 3,700 kilometres on both the North and Baltic Seas.

One of its most popular seaside resorts is Rostock, attracting roughly 38,000 visitors per day.

A big attraction of this former east-German port city are its white sandy beaches, that spread out along Mecklenburg's Baltic Sea coastline.

The 19km coastline controlled by Rostock council includes 37 nudist sections, attracting naturists from all over the country and further afield.

Until now, sunbathers in swimwear have been tolerated on the nudist sections, but this is all about to change.

Following a spate of complaints from both nudists and non-naked sunbathers, local authorities have decided to enforce a crackdown.

According to new rules published in a 23-paged document, anyone sunbathing on a nudist section must do so without any clothes on.

“The presence on nudist beaches is reserved exclusively for people practising nudism," the document issued by Rostock's tourism authority said.

"Clothed bathing and clothed sunbathing are not permitted."

The rule will be enforced by patrols organised through the city's public order office, the Ordnungsamt.

Anyone who refuses to comply with the new regulations will not face any fines, but will be asked to move elsewhere.

Some councillors have protested against the ban, saying it is unenforceable and that giving nudists exclusive access to beaches is outdated.

Germany was at the forefront of the naturist movement, which started around 130 years ago in the 19th century.

Known as the Freikörperkultur (Free Body Culture), the community-based form of naturism was seen as a way to improve both mental and physical well-being.

It’s a non-erotic celebration of the human form, often practiced in nature, and sometimes connected to athletics.

However, its practitioners are decreasing rapidly, as the movement fails to attract younger members.