Police Scotland has been accused of acting as Donald Trump’s private security force after charging a 61-year-old grandmother with allegedly answering the call of nature amongst the dunes at the would-be US president’s golf resort in Aberdeenshire.

Rohan Beyts, an endurance swimmer, munro-bagger and former social worker, has been charged under section 47 of the Civic Government Act (Scotland) 1982 for urinating “in such circumstances as to cause, or to be likely to cause, annoyance to any other person”. If convicted, she could be fined up to £500.

She said she was visited by police at 10pm on Thursday night after a complaint from the Trump organisation. Police officers told her that Trump staff had photographed her committing the alleged offence late in the afternoon on 11 April on mobile phones.

“There was no-one in view when I – and I am not admitting anything – sat down in the dunes which suggests that they were keeping out of sight,” she told the Sunday Herald. “I was doing nothing wrong,” she stated. “Actions like this are designed to intimidate. I’ve nothing to be ashamed or embarrassed about.”

She was accused by the Trump organisation, however, of causing offence. “Offensive behaviour such as this is a matter for the police,” said Trump’s Scottish spokeswoman, Sarah Malone. “This disgusting and shameful act took place in broad daylight in full view of our staff and guests by an individual who has been disruptive in the past.”

Beyts said she had never been charged with any offence before. She is an active environmentalist and has protested against Trump’s golf course in the past. She does voluntary work for the John Muir Trust, which protects wild land – including clearing up other people’s wastes. She famously swam the Gulf of Corryvreckan, site of the world’s third largest whirlpool, to raise money for the trust in 2011.

When she does have to relieve herself while out walking she follows the Mountaineering Council of Scotland’s advice on “where to go in the great outdoors”, she said. Beyts accepted that the police have to follow up complaints of alleged wrongdoing. “But they came to my home at 10pm regarding what is essentially a minor offence,” she said. “My first thought was that something had happened to one of my children and this caused me a lot of distress.”

The filmmaker, Anthony Baxter, was arrested by police in 2010 when he was making a documentary about the way Trump treated local residents. “The police are once again behaving like a private security force for Donald Trump,” he said. “What a complete waste of police time and resources.”

He added: “This is a sorry reminder that Trump’s luxury golf development is a gated community for the super rich where ordinary people are not welcome. Spying Trump cameras and security guards keep a watch on what was once a wilderness area of outstanding natural beauty.”

The Scottish Greens accused Trump of “bullying and heavy-handedness”. The party’s justice spokesperson and former police officer, John Finnie, urged Police Scotland to drop the charge. “Few folk will not have had cause to take a comfort break and, so long as appropriate steps are taken to ensure privacy, there should be no issue,” he said.

“The police should reflect on their actions. If the matter is reported further then the Fiscal should place the report in the bin and have a word in the lug of the officers involved.

“Hopefully, after reflecting, the authorities will share my opinion that the more appropriate recipients of police attention are those who think it acceptable to film someone taking a discrete comfort break.”

After Beyts told her story on social media yesterday, she received dozens of messages of support. “You are wonderful granny Beyts,” said Rosanne McWilliams. “May your piss flow long and amber for many moons to come...God love ya.”

Davie Newton said: “A mass act of pissing disobedience might be in order if this is actually taken to court. Police should be ashamed as should the folk that sent them to you.”

Police Scotland confirmed that Beyts had been charged under section 47 of the Civic Government Act (Scotland) 1982. A spokesperson said: “Police Scotland can confirm that a 61-year-old woman has been charged in connection with an incident at Trump International Golf Club, Balmedie, Aberdeen on April 11. A report will be submitted to the Procurator Fiscal.

“Police Scotland has a responsibility to investigate any and all reports of criminal activity.”