Thousands of protesters in Belgrade on April 25 took to the streets to demand a probe into a multi-billion euro riverside building project in the Serbian capital.

Protesters displayed a yellow duck, a symbol of their opposition slogan, “Let’s Not Sink Belgrade,” near the Sava river where residential buildings, hotels, and shopping mall will be built.

The protesters demanded 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.

The 3 billion euro project, which government officials say should turn Belgrade into a tourism hub, will be developed by a joint venture between 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 and an average monthly wage of 400 euros.