Bangladesh's main opposition party named the exiled eldest son of Khaleda Zia as its acting head on Friday, a day after a court jailed its leader for corruption.
Zia, 72, spent the night in jail after she was sentenced to five years over the embezzlement of $252,000 meant for an orphanage, a charge she has dismissed as politically motivated.
Her son Tarique Rahman, who was also found guilty of involvement in but escaped prison because he lives in London, will be the party's interim leader.
"He is the new acting chairman in accordance with the party's constitution," Bangladesh Nationalist Party (BNP) secretary general Fakhrul Islam Alamgir told AFP.
The conviction could prevent Zia from running in a general election slated for December, although she is expected to appeal.
She spent the night in what her party officials say is a disused jail in the old part of Dhaka.
"She is in isolation," said Alamgir, adding that her conviction is "part of a government blueprint to establish one-party rule".
Rahman, 53, fled to London in 2008 after he was detained by an army-backed government for more than 18 months.
In 2016, he was convicted in absentia and sentenced to seven years in jail on charges of money laundering.
Prosecutors have also sought his death sentence over a 2004 grenade attack at a rally of current Prime Minister Sheikh Hasina in which more than 20 people were killed and she was injured.
The BNP plans to stage nationwide demonstrations late Friday afternoon in protest at the verdict.
Alamgir said opposition parties had been barred from holding protests and alleged curbs on media freedom by the government.
Violence erupted in major cities across Bangladesh as news of the guilty verdict spread on Thursday, with BNP supporters clashing with police and activists from the ruling party.
Police fired rubber bullets at demonstrators in the northeastern city of Sylhet. At least four people have been injured in the clashes.
Authorities have for days been on high alert for protests in tense Dhaka, where political demonstrations by BNP and its Islamist allies in 2014 and 2015 left nearly 200 people dead.
Around 3,500 opposition activists and officials were arrested in a sweep by security forces ahead of the verdict, according to the BNP.
Zia is a former ally turned arch-foe of Hasina. Her party boycotted 2014 polls in which Hasina was re-elected but is expected to contest the upcoming general election.