A campaign has been launched on a social networking site calling for the closure of a nudist beach after claims it has become a "haven for swingers and perverts".
The group on Facebook was set up after reports that people had witnessed gay sex in sand dunes in the upmarket resort of Holkham Bay, Norfolk.
A Norfolk police spokesman said officers were investigating reports that people had been acting in an "inappropriate manner".
One campaigner, who posted a message on the Facebook page, wrote: "My last three visits to the beach have seen me propositioned twice. I've witnessed gay sex in the sand dunes and men walking around 'playing'.
"I've reported this to the wardens and local PCSO (police community support officer) but nothing has been done.
"The beach used to be a lovely place to go but now it's a haven for swingers and perverts who won't take no for an answer."
Andrew Welch, of British Naturism, stressed the incidents did not involve "genuine naturists".
"This type of thing is rare but we are aware of these reports," he said.
"Most of the time we don't have any issues at all. When they do arise, we want to stamp them out.
"What I would like to stress is that this does not involve genuine naturists. We abhor that behaviour like everyone else.
"This is not an everyday occurrence and we are working with the authorities to resolve the matter. We don't think it's necessary to close the beach."