BELGRADE (Reuters) - Thousands protested in central Belgrade on Tuesday against Prime Minister Aleksandar Vucic’s government and demanded a probe into a multi-billion euro riverside building project in the Serbian capital.

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A yellow duck, a symbol of the movement “Let’s Not Let Belgrade Drown” opposing the project, was displayed under flags marking the area along the Sava river where the Dubai-style residential buildings, hotels and shopping mall will be built.

The protesters demand a probe into an incident last year when masked men carried out secretive nighttime demolitions to clear part of the site while public attention was distracted by a parliamentary election. Critics charged the government did not consult the public sufficiently.

“We are protesting because of government’s violence to its own legal system, and corruption. This is our attempt to fight for the rule of law,” Zoran Dimitrijevic, 44, an electronics engineer from Belgrade.

The 3 billion euro project, which government officials say should turn Belgrade into a regional tourism hub, will be developed by a joint venture formed by the Serbian government and the Dubai-based company Eagle Hills.

Protesters have organized several anti-government rallies, demanding an inquiry into the demolitions, but the perpetrators have never been identified.

Critics cite the absence of public tenders for the project and question its economic viability in a country with double-digit unemployment an average monthly wage of 400 euros ($437).

Jovo Bakic, a philosophy lecturer, told the protesters: “We want to send a message to Vucic - we are not subservient to false sultans, Vucic you are Erdogan.”

Vucic, who won the presidential election in early April and will take over later this month, told Tanjug news agency protests are not harming his popularity.

His new post will be largely ceremonial, but he is expected to maintain influence through his Serbian Progressive Party and to continue a balancing act between the West and Russia.

Dobrica Veselinovic, head of “Lets Not Let Belgrade Drown”, said the movement will develop into a political party and take part in the 2018 local elections.

“We tried to appeal to politicians and we don’t have any other option but political activity to achieve our goals,” he told Reuters.

Protesters were due to march to the government building later in the evening.

(This story adds ommitted words in paragraph 11 and changes she to he in paragraph 12)