An activist (C) is observed by security personnel after attaching herself to the tennis net. AFP

The French Open semi-final between Casper Ruud and Marin Cilic was held up for 13 minutes Friday when a protestor ran onto the court and tied herself to the net.

The woman leapt from the Court Philippe Chatrier crowd during the sixth game of the third set.

She wore a shirt which bore the slogan: "We have 1028 days left."

She was eventually removed from the court while the players headed back to the locker room.

The match later resumed, Ruud running out a 3-6, 6-4, 6-2, 6-2 winner to become the first Norwegian man to reach a Grand Slam final where he will meet 13-time champion Rafael Nadal.

French Open organisers said the "environmental activist managed to get onto Philippe-Chatrier court and attached herself to the net with metal wires and glue".

"The security team needed to formally identify the objects she used to get onto the court before they could remove her."

Organisers added: "The young woman, of French nationality, entered the grounds with a valid ticket early in the day.

"She was then handed over to the police."

Agence France-Presse