Al-Jazeera says one of its senior journalists has been arrested in Germany at the request of Egypt.
Ahmed Mansour, who works for the channel's Arabic-language service, was detained as he tried to board a flight from Berlin to Qatar.
A German police official said Egyptian authorities had issued an international arrest warrant for Mr Mansour.
A court in Egypt's capital Cairo sentenced him to 15 years in prison in absentia last year on torture charges.
Al-Jazeera says the claims made against Mr Mansour, who has dual British and Egyptian citizenship, are absurd and false.
"I am still under arrest at Berlin airport, waiting to be taken before an investigating judge," Mr Mansour, 52, tweeted on Saturday night.