BELGRADE (Reuters) - Thousands of protesters marching in Belgrade to mark the anniversary of the assassination of a Kosovo Serb leader accused the authorities on Wednesday of covering up for the perpetrators of the unsolved killing.

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The march, the seventh such anti-government protest since December 8, took place on the eve of a visit by Russia’s President Vladimir Putin, an event expected to boost the popularity of President Aleksandar Vucic, who also heads the ruling Serbian Progressive Party (SNS).

Protesters brought together by the Alliance for Serbia, a loose grouping of 30 opposition parties and organizations, marched in silence in the evening in tribute to Oliver Ivanovic, gunned down a year ago in the Kosovo town of Mitrovica.

“This is not only about Oliver, who was a man of peace, this protest is also about the climate of fear-mongering, this is because of a regime that is intimidating its own citizens,” said Nenad Nikolic, a 23-year-old student.

Ivanovic, 64, was shot dead on Jan. 16 as he arrived at his party office in Mitrovica, a town bitterly split between Kosovo’s majority ethnic Albanians and minority nationalist Serbs, who dominate the northern region surrounding Mitrovica.

He had been facing retrial over killings of ethnic Albanians during Kosovo’s 1998-99 guerrilla uprising against repressive Serbian rule. Kosovo gained independence from Serbia in 2008 and Ivanovic subsequently became known as a relative moderate for advocating dialogue and compromise with Kosovo Albanians.

Ivanovic also became one of the chief interlocutors for NATO, U.N. and EU officials based in Kosovo to help steer it toward stable democracy and rule of law.

“This is a symbolic day because we are not only marking the slaying of a great man, we are marking one year of a cover-up by the state and Pristina as well,” Stana Ilic, 59, said.

“I hope this murder will be resolved once Vucic and his clique are replaced,” she said.

Three Serbs were arrested in connection with the killing in November 2018 when a special police unit sent by the Kosovo Albanian government in Pristina carried out a raid in the Serb-dominated north side of Mitrovica. They have yet to be charged.

On Wednesday protesters marched toward the biggest Orthodox church in Serbia, the Saint Sava Church, a site which Putin will visit. Dozens of thousands of SNS supporters are expected to come to the church on Thursday to greet the Russian leader.

Since he took power in 2012, Vucic has been performing a delicate balancing act between Serbia’s goal to join the European Union and maintaining close ties with Orthodox Russia.

Vucic and his coalition have a majority of 160 deputies in the 250 seat parliament, but protests could shake their popularity.

“Dissatisfaction is there, it is a question of time if there is going to be more sustained risk to the government,” Florian Bieber, Balkans expert at the University of Graz, told Reuters.