The arrest came days after Prime Minister Giorgi Gakharia resigned following a disagreement over whether to take the prominent politician into custody.
Melia, who heads the United National Movement (ENM) opposition party, had been accused of inciting violence at street protests in June 2019, a charge he has dismissed as politically motivated.
A Tbilisi court last week ordered that he be taken into custody for allegedly failing to post bail. The Interior Ministry at the time announced it was postponing carrying out the order to detain Melia following the resignation of Prime Minister Giorgi Gakharia.
Live television footage showed Melia, the leader of the ENM, being dragged from the party headquarters to be placed in pre-trial detention.
Hundreds of riot police used tear gas against Melia’s supporters and the leaders of all of the country’s opposition parties, who have been camped out in the building since February 17, the Mtavari TV live pictures showed.
Dozens of opposition supporters were detained.
“Shocked by the scenes at [ENM] headquarters this morning,” British ambassador Mark Clayton wrote on Twitter. “Violence and chaos in Tbilisi are the last thing Georgia needs right now. I urge all sides to act with restraint, now and in the coming days.”
Melia’s arrest came a day after the Georgian parliament approved a new government led by Prime Minister Irakli Garibashvili following the resignation on February 18 of Gakharia, who said his move had been prompted by a disagreement with his own team over the order to detain Melia.
Garibashvili and his proposed cabinet were supported by 89 deputies with two opposed in the 150-member parliament, where the ENM and smaller parties are boycotting proceedings.
The political scene for the Caucasus nation’s 4 million people has been on the brink of crisis since October elections that were dominated by the Georgian Dream party but which independent monitors say were marred by irregularities.
Gakharia had said that Melia’s arrest was unacceptable if it threatened to fuel political divisions in the Caucasus country of 3.7 million people.