KIEV - Thousands of people rallied Sunday in central Kiev to demand the release of detained former Georgian leader Mikheil Saakashvili and the impeachment of his rival, Ukrainian President Petro Poroshenko.

Saakashvili, 49, who entered Ukrainian politics after serving as president of Georgia, was arrested last week in Kiev, accused of trying to stage a coup sponsored by Russia. "The authorities have crossed a red line. You don't put opponents in prison," said Saakashvili's wife, Sandra Roelofs, as marchers brandished anti-government and anti-corruption slogans. Saakashvili was president of Georgia from 2004 to 2013 but acquired Ukrainian nationality and served as a governor in Ukraine before falling out with Poroshenko. "I am very afraid that our government is about to collapse. Ukraine is headed for the abyss, the people are getting ever poorer. Corruption is everywhere and the authorities do nothing," one marcher, Nikolai Sharapa, 58, told AFP.

Ukrainian security services arrested Saakashvili on Saturday following a botched attempt several days earlier when supporters swarmed the van where he was being held.