A celebrity magazine has been hit with maximum fines after snapping topless photos of the Duchess of Cambridge, but the compensation fell well short of the €1.5 million ($A2.2 million) sought by the royal couple.

A French court ruled that celebrity magazine, Closer, had invaded Kate Middleton’s privacy by photographing her with a zoom lens while she sunbathed topless on a terrace at a private chateau while on holiday with Prince William in the south of France in 2012. The property was owned by Viscount Linley, a nephew of Queen Elizabeth II.

Both Laurence Pieau, an editor of the magazine’s French edition, and Closer owner Ernesto Mauri were each handed fines of €45,000 ($A66,776).

Two photographers from a Paris agency, who denied taking the photographs, were ordered to pay smaller fines of €10,000 ($A15,000) each after also being convicted under French privacy laws.

The court ruling followed Monday’s announcement that the royal couple are expecting their third child.

The office of the Duke and Duchess of Cambridge said the British royal couple was pleased with the ruling and that the matter was now closed.

The BBC reported the royal couple was expected to donate the funds to charity.

The couple had “wished to make the point strongly that this kind of unjustified intrusion should not happen”, according to a statement from Kensington Palace.

The damages ordered by the court did not come close to the €1.5 million initially sought by the Cambridges, who filed the suit for what they believed was a “grotesque” breach of privacy.

At the time they were printed, the photos – captured from up to one kilometre away from where Kate was sunbathing – were slammed by Prince William as “particularly shocking” in light of paparazzi intrusion into the life of his late mother, Princess Diana.

Closer magazine’s lawyers had sought to justify publication of the photos on public interest grounds, claiming they disproved rumours circulating at the time that Kate may be anorexic.

Jean Veil, a prominent French lawyer hired by Kate, said during the trial that the article that accompanied the photos was only a pretext for publishing the pictures.

Prince William opens up on pregnancy

Prince William and Kate Middleton are expecting their third child. Photo: PA Wire

Prince William revealed on Tuesday (UK time) that Kate is well after an “anxious” start to her pregnancy.

In his first public appearance since it was announced he is to become a father for the third time, Prince William said: “It’s very good news.”

He also said there was “not much sleep” being had at the main family home of Kensington Palace with the Duchess of Cambridge, who is less than 12 weeks pregnant and suffering from severe morning sickness.

Prince William thanked well-wishers during a visit to the National Mental Health and Policing Conference in Oxford, where he addressed officers as the event’s keynote speaker.

“We need Catherine (Kate) to get over this first bit and then we can start celebrating,” he said.

“It’s always a bit anxious to start with, but she’s well.”

He added: “There’s not much sleep going on at the moment.”

-with AAP