Tens of thousands of people have gathered in the center of the Macedonian capital Skopje to demand the resignation of conservative Prime Minister Nikola Gruevski.

The Sunday protest follows the release of a massive cache of wiretapped conversations by the head of the opposition Social Democrats, Zoran Zaev. He claims that Gruevski was behind the mass wiretapping of more than 20,000 Macedonians.

The conversations purport to reveal corruption at the highest levels of government, including mismanagement of funds, spurious criminal prosecutions of opponents and even attempted cover-ups of killings.

Zaev said those conversations were leaked to him by "patriots" in the domestic intelligence service. He demands the formation of a caretaker government that will organize new elections.

Gruevski angrily rejects the accusations.