Parts of Caesarea National Park, one of the country's prime tourist sites, are in danger of collapse due to erosion caused by ocean waves, the Israel Nature and Parks Authority warned on Saturday. The authority said immediate steps must be taken to prevent further damage.

A senior figure at the Israel Antiquities Authority described the situation as a national disaster.

Another official, the antiquities authority's head of marine archaeology, said the erosion of sand and rock has been getting worse for years.

"At the beginning of last year the beach at the ancient port had to be closed because there was no more sand," said the official, Kobi Shavit. He added that restaurants in the area were in danger of collapse and parts of the rocky promontory north of the port, which is covered with antiquities, is collapsing, as are parts of the ancient port itself.

"The picture is very worrisome, although it can still be saved," Israel Nature and Parks Authority director Eli Amitay said.

According to Shavit, Israel has proposed Caesarea to the United Nations cultural arm UNESCO as a World Heritage Site. It was built as a port city mainly by Herod the Great at the end of the Second Temple period, but also contains significant remains from Crusader times.

A plan devised by a steering committee of agencies overseeing Caesarea National Park calls for the construction of a breakwater and lengthening the pier, built 50 years ago.

"The intent is to turn the area into a kind of protected pool," Shavit said, adding that artificial sand will have to be brought in as reinforcement. The Israel Nature and Parks Authority estimates that around NIS 60 million is needed to properly protect the site.