The leader of Macedonia's opposition Social Democrats, Zoran Zaev, has been charged by police with attempting to topple the conservative government of Prime Minister Nikola Gruevski with the help of a foreign intelligence service.

Zaev has denied the charge, saying the government was trying to intimidate him in order to prevent the publication of alleged evidence of criminal wrongdoing by Gruevski’s government.

Gruevski said at a news conference on Saturday that Zaev had tried to blackmail him into resigning and calling early elections during several meetings the two of them had had in late 2014.

According to Gruevski, Zaev claimed to have obtained potentially damaging evidence against the cabinet with the help of an unnamed foreign intelligence agency.

Macedonian TV station Sitel on Monday aired a video footage allegedly recorded during one of the meetings between Gruevski and Zaev.In the video the prime minister asks Zaev from where he had obtained the purported evidence and Zaev replies he had received it with the help of a foreign intelligence service.

Zaev wasn't arrested but was ordered to hand over his passport to the authorities

The Social Democrats, the largest opposition party, have been boycotting parliament since Gruevski's VMRO-DPMNE party won April 2014 general election and formed a coalition government. The Social Democrats allege VMRO-DPMNE’s victory was won through electoral fraud.

The EU, US and Russia called on the authorities in Skopje to ensure transparent and unbiased investigation into the charges of attempted coup d’?tat.

 “We call upon the authorities to meet the highest standards on rule of law, transparency, protection of freedom of speech as well as legal independence during the process, in order to ensure the integrity of the democratic process in Macedonia,” the US embassy to Macedonia said.

A EU spokesperson commented: “These are very serious charges and we recall the inalienable right of an independent and transparent investigation in case of any alleged wrongdoing, with full respect of the rights of the defendants in accordance with the law and international standards, including the principle of presumption of innocence.”

Russia’s Foreign Ministry said in a statement that “the destabilisation of the situation in friendly Macedonia might dangerously escalate persisting inter-ethnic frictions there.”

“We hope that a thorough investigation of the incident is conducted in order to ensure stability and security in Macedonia. We are calling on all political forces of this country to act in line with constitutional democratic institutions and address existing problems through dialogue.”