Iranian rapper Amir Tataloo has been detained by Turkish authorities in Istanbul after he was flagged as a wanted person by Interpol, police say.
Turkish police said Interpol issued a "red notice" for Tataloo, real name Amirhossein Maghsoudloo.
The notice, which is not an arrest warrant, was for a drug-related issue, police said.
However, police said Tataloo was detained for a visa violation. No decision on deportation has been made.
A popular but controversial figure in Iran, the rapper is known for his outspoken criticism of the country's government.
In his songs and on social media, Tataloo often speaks out against the Iranian government's record on human rights and press freedoms.
Iranian police have accused Tataloo of "encouraging citizens, especially the youth, to use drugs", according to a statement quoted by Iran's semi-official ISNA news agency.
Prior to his detention, Tataloo was preparing to travel to the UK, where he was due to play a concert in February.
On Tuesday, Tataloo posted a picture of himself in handcuffs to his Instagram story. A change.org petition calling for Tataloo's release has received more than 70,000 signatures.
Speaking to TV channel Iran International, Tataloo's social media manager said "if Amir is handed over to Iranian police, it is unclear what is going to happen".
An Interpol red notice is a request to law enforcement worldwide to locate and provisionally detain a person.
Interpol's role is to assist the national police force in identifying and locating the individual with a view to their arrest and extradition. However, Interpol cannot compel authorities in any country to arrest or deport someone.
Who is Amir Tataloo?
Tataloo was reportedly living in Turkey to pursue his career as a rapper and musician. The rapper, whose music has been described as a blend of pop, rap, jazz and R&B, did a live performance for BBC Persian in 2018.
One of the most popular Iranians on social media, Tataloo has 2.4 million followers on Instagram and 1.3 million followers on Facebook.
He has previously encouraged his followers to vote for conservative and hard-line figures in the 2017 presidential elections, sparking debate and controversy.
But in recent years, Tataloo has been critical of the Iranian government, which have banned his music, deeming it Westernised and immoral.
In 2013, Tatalou was arrested by Iran's morality police and later released. Then, in 2016, he was arrested and imprisoned, reportedly on charges of spreading depravity among youth.