George Clooney is not mincing words about his frustration with photos of his infant twins published by a French gossip magazine.

In a statement to USA Today on Friday, Clooney says the images, published on the cover of the French-language Voici magazine and making the rounds online, were taken "illegally."

"Over the last week photographers from Voici magazine scaled our fence, climbed our tree and illegally took pictures of our infants inside our home," he says in the statement.

"Make no mistake the photographers, the agency and the magazine will be prosecuted to the full extent of the law. The safety of our children demands it."

Clooney and wife Amal Alamuddin Clooney welcomed their twins in June, a boy named Alexander and a girl, Ella.

The announcement was met with joy from fans who, over the last few years, watched Clooney reverse his positions on what he'd never, ever do: Settle down, marry again (he was married to actress Talia Balsam from 1989 to 1993) or have kids.

The family took their first trip earlier this month, making the first time the Clooneys had been seen in public since the birth of the twins. Paparazzi cameras captured George Clooney, wife Amal, and their twins landing in Milan, Italy. Clooney's Lake Como villa, where he spends the summer each year, is a short ride away.

Clooney's threat of prosecution likely would not be possible in the US or UK, though it may be in France, where press freedoms can be restricted by privacy laws designed to prevent the sort of surreptitious pictures Clooney is upset about. In 2012, photographers snapped sneak shots of Duchess Kate of Cambridge sunbathing topless at a villa in the south of France.

Editors of the French gossip magazine, Closer, and a few other European publications published them, to Prince William's outrage. He instructed his lawyers to pursue criminal and civil against the publishers and the photographer. Six journalists went on trial in May outside Paris on invasion of privacy charges.

Clooney has been vocal about his opposition to the tactics of paparazzi photographers and tabloids in the past, urging photographers to respect the driving laws after a collision in 2007, and writing an op-ed for USA Today in 2014 about a report in the Daily Mail.

"The Daily Mail, more than any other organisation that calls itself news, has proved time and time again that facts make no difference in the articles they make up," he wrote. "And when they put my family and my friends in harm's way, they cross far beyond just a laughable tabloid and into the arena of inciting violence."

The actor has been crusading against the paparazzi and their tabloid enablers for 20 years, ever since the 1997 death of Princess Diana, whose car crashed while being chased through a Paris tunnel.

Days after her burial, Clooney held a news conference in which he lambasted the mainstream media, telling them: "You've deflected responsibility. Yet I wonder how you sleep at night. You should be ashamed! I watch as you scramble for high ground, take your position on CNN saying there is a market for this and you are just supplying the goods." He begged those present, "Do not purchase your news. Do not use tabloids as a source. You define the difference between tabloid and legitimate news."

USA Today