The US Open semi-final between Coco Gauff and Karolina Muchova was held up after a protest in the stands.

Three people, wearing T-shirts bearing the words ‘fossil fuels’ began shouting after the first game of the second set, forcing play to be stopped.

American teenager Gauff and Czech 10th seed Muchova initially stayed on the court for about 10 minutes while security tried to deal with the situation.

The Arthur Ashe crowd at one point began chanting “kick them out” with the protesters apparently being difficult to shift.

“Are they like talking to them or are they going to remove them?” Gauff asked chair umpire Alison Hughes and tournament referee Jake Garner.

She then spoke to her coach, Brad Gilbert, saying “they say they are negotiating, like it’s a hostage situation. What should I do?”

Both players eventually left the court with Gauff leading 6-4 1-0.