An Egyptian dissident who was extradited to the United Arab Emirates after criticizing its government on social media has been detained for more than seven months without a trial, in a case that his lawyers warn sets a dangerous precedent for transnational repression.

Abdulrahman al-Qaradawi, a poet and anti-authoritarian activist, had traveled to Syria in December to celebrate after rebels toppled the Syrian dictator Bashar al-Assad. From there, he recorded a video expressing hope that the Middle East’s other autocratic rulers would also fall. In the video, posted online, he warned that “the shameful Arab regimes and Arab Zionists in the United Arab Emirates, Saudi Arabia and Egypt” could conspire against the new Syria.

Within days, Mr. al-Qaradawi — the son of the late Islamic scholar Yusuf al-Qaradawi — was arrested by Lebanese security forces as he crossed the border into Lebanon. But he was not deported to Egypt, where a prison sentence had been issued in absentia against him in 2016, on charges connected to speaking out against the Egyptian government. Or to Turkey, where he lived in political exile. Instead, Lebanese authorities sent him to the Emirates — a country more than 1,000 miles away, to which he had no connection.

Mr. al-Qaradawi’s unusual case has shed light on the long arm of the Emirates as it exerts political influence across the Middle East. A federation of seven sheikhdoms on the Persian Gulf, the country is a close U.S. ally that has translated its oil wealth into immense economic and political power.

Detained on Dec. 28, Mr. al-Qaradawi was on a flight to the Emirates by Jan. 8. His case appears to be the first in which a broad Emirati law “countering rumors and cyber crimes” was applied beyond the country’s borders.

Until August, Mr. al-Qaradawi’s family had seen him only once, during a 10-minute visit in March, and otherwise had no contact with him, nor did they know where in the Emirates he was being held, according to Rodney Dixon, a London-based lawyer who is working with the family. They were granted a second visit on Monday, several weeks after The New York Times sent the Emirati government questions about his case.