EVER since Diana, Princess of Wales, was snapped in an amorous clinch with Dodi Fayed in a yacht off the French Riviera, celebrities have been seeking ways to enjoy their holidays while avoiding the glare of the paparazzi.

Even Helen Mirren’s advancing years failed to stave off photographers who caught her in a bikini in Italy last year.

Now Roman Abramovich, the Russian oligarch, appears to have come up with a novel solution to protect his privacy.

In a move that could eventually be copied by all discerning billionaires, Abramovich has installed an anti-paparazzi shield on his newest vessel, the world’s biggest and most expensive private yacht.

The high-tech system on Eclipse, a mega-yacht measuring up to 557ft, relies on lasers to block any digital camera lenses nearby.

The boat, which has reportedly more than doubled in cost to £724m since it was commissioned three years ago, glided out of port in Hamburg last week on its maiden voyage. On board were 150 engineers and maritime experts who will put it through its paces over 10 days. One witness described the boat as “a great white castle on water”.

The yacht — the fourth in Abramovich’s private fleet — drips luxury. It boasts two helipads, two swimming pools — the larger of which doubles up as a dance floor when drained — and 6ft-wide home cinema screens in all 24 guest cabins.

The master suite features a retractable roof, allowing the Chelsea football club owner and his girlfriend, Daria Zukhova, a former model, to sleep under the stars.

Mindful of a rise in piracy on the high seas, the yacht has a hull and windows capable of withstanding a missile attack and a mini-submarine for emergencies. Once it leaves the Blohm + Voss German shipyard, it will be fitted with a missile defence system in France.

Abramovich, 42, has been making regular trips to Hamburg to oversee construction and has demanded modifications that have led to its cost rocketing from £317m.

He is due to take delivery of the yacht on December 22 — treating himself to the ultimate Christmas present.

The oligarch is then widely expected to show off his new toy at the 2010 World Cup in South Africa, docking the vessel off Cape Town and flying to matches by helicopter — assuming that Russia qualifies for the tournament.

The definitive size of Eclipse has not been confirmed because of confidentiality clauses in the construction contracts. However, a spokesman for ThyssenKrupp, which owns the shipyard, said this weekend: “It will be the largest private yacht of all time.”

The current record is held by Dubai, a 524ft vessel owned by Sheikh Mohammed bin Rashid al-Maktoum, the prime minister of the United Arab Emirates.

Abramovich already owns the world’s biggest private jet, a Boeing 767 nicknamed “the Bandit”.

His largest yacht until now has been Pelorus, a relative minnow at 377ft.

Eclipse is likely to require a crew of at least 60 people, said to include a security team of hand-picked former veterans of the French Foreign Legion.

However, the boat’s most unusual feature is perhaps the anti-paparazzi “shield”.

Infrared lasers detect the electronic light sensors in nearby cameras, known as charge-coupled devices. When the system detects such a device, it fires a focused beam of light at the camera, disrupting its ability to record a digital image.

The beams can also be activated manually by security guards if they spot a photographer loitering.

Last week it emerged that Abramovich — whose fortune has fallen by an estimated £4.7 billion to £7 billion in the recession, according to The Sunday Times Rich List — has splashed out £55m on a 70-acre estate on the Caribbean island of St Barthélemy. The exclusive retreat looks out onto Gouverneur Bay, where the oligarch will be able to moor his new yacht.

Despite the estate featuring a large villa, Balinese-style bungalows, swimming pools and two floodlit tennis courts, it has a road running through it allowing access to the public beach — described by Forbes magazine as one of the finest in the world for topless sunbathing.

Additional reporting: Robert Watts

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