The activist group Extinction Rebellion has staged a non-disruptive silent vigil during the first Grand Slam of the season at Melbourne Park, in their opening protest of the year.

Tennis fans leaving the venue were met with large banners and flags, with messages demanding climate change action.

"This summer we have seen the tennis and cricket disrupted by smoke as bushfires rage across the country, and predictions are for more and more disruption in future years as temperatures increase," Extinction Rebellion spokesperson Catherine Strong said to 7news.

"We are holding this non-disruptive action to show solidarity with all those affected by climate change in this country, from the players who have been on court in hazardous conditions, to the firefighters who will always be on the frontline of this crisis, to those left homeless and the billion wildlife casualties.

"Our message is that the ball is in our court, all Australians must act together to save our beautiful country."

The group also raised money for bushfire-affected communities but did not disrupt the tennis.

"On this trajectory, centre court could be unplayable within years," the group's Brad Homewood told 3AW.

"We have already seen elite players pull out of tennis matches because air has been unbreathable due to bushfires.

"We are also backing up Greta's [Thunberg] call for Roger Federer to disassociate with sponsor Credit Suisse.

"Our first key demand is for the Government to declare a climate and ecological emergency."

The current bushfire death toll stands at 33, with fires still raging through parts of New South Wales.