Casiraghi, third in line to the throne in the principality and son of Princess Caroline, filed the complaint on Saturday in civil court in New York saying that he and three other men were attacked by former restaurateur Adam Hock, 47, at The Double Seven club in New York's trendy Meat Packing District.

The 24-year-old also accused the club and owner Jeffrey Jah of negligence.

The lawsuit seeking compensation comes months after Casiraghi and three of his friends filed criminal complaints against Hock accusing him of hitting them in the face in a fight that erupted in the club in the early morning hours of February 18.

Casiraghi and the three friends, including Stavros Niarchos, a Greek shipping scion and former boyfriend of hotel heiress Paris Hilton, were drinking with Hock and Jah in the Double Seven's VIP area.

"On February 18, 2012, plaintiffs were assaulted, struck and attacked by defendant Adam Hock," the complaint said. "Plaintiffs did not consent to the physical contact."

Hock's lawyer Sal Strazzullo maintained that Hock had acted in self-defence and that they would respond within a month to the complaint.

"My client was the one who was attacked by three individuals and we're going to stand by those facts," he said. That Casiraghi was filing a civil complaint while the criminal complaints were still pending indicated those allegations were likely to be dismissed, he added.

The complaint said Hock was obviously drunk and blamed the club and Jah for serving him alcohol. Jah and representatives for The Double Seven were not immediately available for comment.

Casiraghi accused Hock of defamation for calling him and his friends "drunk entitled guys who felt they deserved the prime table with the most beautiful girls" and saying he and his friends were inappropriately touching and "grabbing" women.

He also lodged a defamation charge against Strazzullo for allegedly saying Casiraghi and his entourage had struck first.

Casiraghi, who lives in Italy, did not state how much he was seeking in compensatory and punitive damages.

He is the son of Princess Caroline of Monaco and her second husband, Stefano Casiraghi, who was killed in a boating accident when Pierre was a young child. He is also the grandson of the late Hollywood actress Grace Kelly.