"The dust and the noise are stopping us from enjoying this idyllic place."
He added that workers had even advised one woman to make the most of the beach now "because soon there'll be no access at all".
Another resident said the builders had told him they were working for the Saudi royal family. "They advised me not to hang around in the area for long."
Blandine Ackermann, the president of the Association for the Defence of the Golfe-Juan and Vallauris Environment, threatened to file a legal complaint unless the beach remained open and was restored to its original condition.
"This concrete slab is taking up half the beach. It's an outrage," she told the Daily Telegraph. She added: "If King Fahd's son feels unsafe on the beach then he should stay in his villa. Already the property has very high walls and is totally closed. It's a fortress. He never swims anyway. I've never seen anyone from the villa swim there.
"They have decided to annex part of the beach but it doesn't belong to them. We're not in Saudi Arabia here," she said. "They think they can do here what they do at home."
When the Mayor of Vallauris, Michelle Salucki, was informed of the works, she called police, who were sent to stop the construction and ensure access to the beach via the tunnel remained open. Local authorities, however, confirmed the beach would be closed to the public during the impending visit by Saudi royalty, for safety reasons.
Philippe Castanet the sub-prefect of the nearby town of Grasse, did concede that work had started prematurely and said talks were continuing over how best to ensure the family's security during the visit.
More talks with representatives of the Saudis were taking place yesterday. Castanet, however, insisted that for safety reasons "the public beach should be totally closed off to the public for the entire stay of the family".
He said it was undecided whether to use "private security guards or policemen", "fencing or not", and "when we can return this area to the public in as short a time as possible".
This is by no means the first run-in between locals and the Saudi royal family at Vallauris. In 1995, King Fahd lost a legal battle to close a coastal path that ran close to his property and was ordered to remove a machine gun pointing out to sea. He was also blocked from building a parking bay for his yacht.
In 2012, environmentalists and anti-corruption group Anticor 06 filed a legal complaint after local politicians granted the Saudis the right to build two huge villas with swimming pools and outside bars worth 64 million ($106.6 million) on nearby protected land around the Chateau Robert, a ruined castle.
The local prosecutor is due to decide shortly whether to pursue an investigation into the complaint.