Around 200 people have gathered in Dublin to show support for Istanbul mayor Ekrem İmamoğlu who has been jailed in Turkey pending a trial over corruption allegations.
Mr İmamoğlu was arrested just days before he was set to be announced as a presidential candidate for the country's 2028 election.
He has vowed to fight the charges, which he has called "immoral and baseless".
His detention has led to widespread protests across the country, with his supporters seeing him as the strongest candidate to go up against current president Recep Tayyip Erdogan in the election.
People from the Turkish community in Ireland have been holding demonstrations in Dublin since Wednesday.
A spokesperson for a group called the Democratic Türkiye Community in Ireland accused authorities of turning Turkey into an "open air prison" and described Mr İmamoğlu’s arrest as a "political coup".
Earlier, a Turkish court formalised Mr İmamoğlu’s arrest, and its decision came as the main opposition CHP (Republican People’s Party) cast its ballots in a long-planned primary to elect him as its presidential candidate.
Observers said it was this looming primary that triggered the move against him.
"This injustice is a direct blow to the people’s right to vote and be elected, showing that citizens’ will can be seized at any moment," spokesperson Ebru Isikli told the crowd in Dublin.
"As Turkish citizens around the world who believe in fundamental rights, freedoms, and the rule of law, we demand the immediate release of Ekrem İmamoğlu and his colleagues.
"We condemn the unlawful system in which anyone who criticizes AKP policies is declared a criminal, and journalists and opposition politicians are imprisoned. We will continue our struggle everywhere.
"As citizens who believe in democracy, both in Turkey and worldwide, we refuse to remain silent in the face of this injustice - and we never will".
The move against Mr İmamoğlu has sparked protests that quickly spread from Istanbul to at least 55 of Turkey's 81 provinces, with police arresting 323 people overnight, officials said.
Riot police used rubber bullets, pepper spray and percussion grenades on the Istanbul protesters.
In Ankara, water cannons were also used.
The unrest has been spreading rapidly, despite a ban on protests in Turkey's three largest cities and a warning from Mr Erdogan that the authorities would not tolerate "street terror".
Additional reporting AFP
