Indonesia says it may ban Hollywood actor Leonardo DiCaprio from returning over his comments on rainforests being cleared for palm oil plantations.
Mr DiCaprio entered Indonesia on a tourist visa and on Sunday visited Gunung Leuser National Park in Aceh.
"A world-class biodiversity hotspot... but palm oil expansion is destroying this unique place," he posted.
If the comments were judged as "incitement", he would be banned in future, a top official told the BBC.
''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, said.
"If DiCaprio's posting in his social media can be categorised as incitement or provocation, we can blacklist him from coming back to Indonesia."
It is not the first time a Hollywood star has run into trouble in Indonesia over their environmental activism.
Star Wars actor Harrison Ford was threatened with deportation in 2013 for "harassing state institutions" after interviewing the then forestry minister about illegal logging.
In posts on his Instagram account, Mr DiCaprio said he was working to save the Leuser ecosystem, "the last place on Earth where Sumatran orang-utans, tigers, rhinos and elephants coexist in the wild".
On Twitter, he posted a link to a petition addressed to the Indonesian President Joko Widodo, calling for the area to be protected.
Some members of the government have accused him of running a "black campaign" to discredit the government and the country's palm oil industry.
But Farwiza Farhan, chairperson of the group Forest, Nature and Environment of Aceh, told BBC Indonesia that the Oscar-winning actor had done nothing wrong.
"The claim that he was trying to discredit Indonesia doesn't make sense because these environment campaigns are local movements," she said.
"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?'"
More on palm oil:
- Palm oil is a multi-billion dollar global industry, almost every major food manufacturer uses it in their products
- It is also used in other household products
- It has lifted many poor farmers out of poverty
- But it has caused controversy because large areas of forests are burnt to make way for plantations
- Indonesia and Malaysia produce more than 80% of the global supply of palm oil