By Aleksandar Vasovic | BELGRADE BELGRADE 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. A yellow duck, a symbol of the movement "Let's **t 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 **t consult the public sufficiently