The design of Shoreline Crescent in Folkestone, Kent, where properties range from £430,000 to £1.8m each, is said to be causing the shrill noise that is so loud those living nearby are being kept awake at night.

Some locals claimed the unusual sound began when the balconies were installed and has been made worse by the recent high winds along the south coast.

Neighbours have vented their fury over the "nightmare" on social media, with one writing on Facebook, alongside a video of the noise as he walked by the building: "Is this the torture we now have to endure all winter?"

Jayne Jones added: "I heard this too and it's like a harp crossed with a xylophone, quite loud, hope they've got triple glazing, this sound would drive me insane."

It is not currently known what exactly is causing the tone, with some suggesting it could be coming from the balconies on the flats creating a "wind tunnel".

Steve Wood said: "Keeps us awake ALL night when it's windy."

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According to the Kent Messenger, multi-millionaire Saga heir, Sir Roger De Haan, is behind the 84-property seafront development, after he bought the town's harbour for £11m in 2004.

New owners are due to move into the block which, so far, is uninhabited.

Some 1,000 new properties are also set to be built along Folkestone's beachfront as part of the project.

Shoreline Crescent said the noise was temporary and should stop when the balcony handrails are installed.

A spokesman for the company said: "Any noise generated during strong winds is only temporary during the construction process.

"The issue will be resolved when permanent handrails are installed on the balconies of certain apartments in the coming weeks."