DUBAI, United Arab Emirates (AP) — Famed Iranian sculptor Parviz Tanavoli said Sunday he has been barred from leaving the country without explanation while trying to travel to Britain.

Authorities confiscated the artist's passport early Saturday morning while he tried to board a flight out of Tehran's Imam Khomeini International Airport. He had been scheduled to give lectures at the British Museum and Asia House in London.

Tanavoli told The Associated Press that he does not know why he was prevented from leaving. Immigration authorities directed him to the country's main passport office, but he came back empty-handed after spending several hours there.

"They said absolutely there is nothing we can do," the 79-year-old artist said. "They tell me it's not political but they don't tell me what it is."

Iranian officials could not immediately be reached for comment.

One of Iran's best-known living artists, Tanavoli is associated with the Saqqakhaneh artistic movement, which began in the 1960s and draws on traditional Persian and Shiite folk themes. His bronze work "The Wall" ("Oh, Persepolis") fetched $2.84 million at a 2008 Dubai auction, then a record price for a Middle East artist.

He travels twice a year between Canada and Iran, and frequently pays visits to Europe and elsewhere without problems, he said. In February last year, he was in the Boston area for his first solo retrospective in the U.S.

Despite his international acclaim, Tanavoli has faced difficulties with Iranian authorities before.

Authorities confiscated 57 pieces of his artwork more than a decade ago. He eventually got 11 back following a court ruling two years ago, only to have them taken away again weeks later.

He is still fighting in the courts to get the artwork back, but said he does not believe that is why he was stopped from leaving Saturday.

"I have followed the rules, I haven't done anything illegal," he said. "I didn't have any hints I did anything wrong."

He plans to continue pursuing his work while he tries to get his passport back, including preparing for a major exhibition at Tehran's Museum of Contemporary Art next year.

Several artists, poets, journalists and activists have been detained in Iran since the government of relative moderate President Hassan Rouhani reached a nuclear deal with world powers last year. The crackdown is widely seen as the work of hard-line elements within the judiciary and security services who oppose loosening limits on social freedoms and Rouhani's strategy of pursuing greater openness to the wider world.

In one of the most recent incidents, police in May arrested eight people for "un-Islamic acts," including female models posting images of themselves without their hair covered online.

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