The arrest of Roman Protasevich and his girlfriend Sofia Sapega after Belarusian authorities intercepted the Ryanair flight on which they were travelling from Athens to Vilnius on May 23 caused international outrage.

Protasevich is now in a rented flat in the Belarusian capital Minsk, his father Dmitri Protasevich told the BBC. He said the authorities had provided no further information.

Sapega was moved to a separate rented flat, her stepfather told the BBC.

Opposition politician Sviatlana Tsikhanouskaya’s office confirmed both were under house arrest.

“The fact that Roman and Sofia were moved to house arrest and are not in cells any more is good news,” Tsikhanouskaya, who is based in Lithuania, said in a statement. “But house arrest does not mean freedom … They remain hostages.”

The Belarusian interior ministry could not immediately be reached for comment.

The European Union imposed economic sanctions on Belarus on Thursday, targeting its main export industries and access to finance.

Belarusian President Alexander Lukashenko, who faced street protests last year over a presidential election which opponents say was rigged, said the interception was justified to prevent a rebellion. He denies electoral fraud.

Protasevich is accused of organising mass riots, and faces up to 15 years in jail if convicted. Sapega has been accused of causing unrest. Their supporters say the accusations against the two are false and dismiss video confessions which they say were made under duress in detention.

Protasevich’s father was quoted by the BBC as saying his son and Sapega were “still under the full control of the authorities” and the charges against them had not been dropped.

(Reporting by Anton Kolodyazhnyy in Moscow and Pavel Polityuk in Kyiv, additional reporting by Andrius Sytas in Vilnius, Writing by Alexander Marrow and Katya Golubkova, Editing by Gareth Jones and Timothy Heritage)