Leonardo DiCaprio has angered the Indonesian Government by warning its rainforests are being destroyed to make way for palm oil plantations.
The Oscar-winning actor, who is a United Nations envoy on climate change and environmental campaigner, entered the country a week ago and visited Aceh's Gunung Leuser National Park.
"A world-class biodiversity hotspot but palm oil expansion is destroying this unique place," he posted on Instagram. "If we don't stop this rampant destruction, the Leuser Ecosystem and the Sumatran orang-utans that call it home could be lost forever."
He also tweeted a link to a petition calling on Indonesian president Joko Widodo to ensure the area is protected.
A top official warned the actor would be investigated for "incitement". "In terms of [his] visa and immigration permit, Leonardo DiCaprio did not do anything wrong.
"He entered and left Indonesia legally.
"But we still investigate," Heru Santoso, spokesperson for the director general of immigration department, told the BBC.
"If DiCaprio's posting in his social media can be categorised as incitement or provocation, we can blacklist him from coming back to Indonesia."
Local environmental campaigners defended DiCaprio.
"The claim he was trying to discredit Indonesia doesn't make sense because these environment campaigns are local movements," Farwiza Farhan, chairperson of Forest, Nature and Environment of Aceh, told the BBC.
"He just gave his support.
"Tourists can come and speak their opinion. When Leo arrived in Medan he was shocked that the haze was so thick, he asked us: 'Is this smoke or clouds'?"
Fellow Hollywood star Harrison Ford also upset the Indonesian Government when he was making a series on climate change called Years of Living Dangerously for US television network Showtime.
Andi Arief, a presidential adviser, accused the Star Wars actor and his crew of "harassing state institutions" and threatened them with deportation nearly three years ago.
DiCaprio used his Oscar-winning speech to warn about the effects of global warming. "Making The Revenant was about man's connection to the natural world," he said.
"We felt in 2015 it was the hottest year on the planet. Climate change is real, it's happening right now, it's the most urgent threat affecting our entire species.
"We need to work right now and stop procrastinating."