Thousands of people have gathered in Serbia's capital, Belgrade, in the largest protest yet against the parliamentary and municipal elections held earlier this month. Protesters accuse President Aleksandar Vucic's governing party, the Serbian Progressive Party (SNS), of orchestrating fraud and are calling for the results to be annulled.

The protest on Saturday marked the culmination of nearly two weeks of street demonstrations against alleged widespread irregularities during the December 17th vote, as noted by international observers. The SNS was declared the election winner with 46.72 percent of the votes, according to preliminary results from the state election commission.

However, the main opposition alliance, Serbia Against Violence, has claimed that the election was stolen, particularly in the vote for the Belgrade city authorities. Protesters waving Serbian flags and holding a banner reading "We do not accept" voiced their support for Marinika Tepic, a leader of the Serbia Against Violence alliance, who has been on a hunger strike since December 18.

"These elections must be annulled," Tepic, who appeared frail and was assisted by two colleagues, declared to the gathered protesters in front of the prominent Moskva hotel.

Serbia Against Violence has led daily protests since December 17, demanding a rerun of the vote. Tensions have soared following violent incidents and arrests of opposition supporters during a protest last weekend.

The rally was supported by students' organizations and an initiative called ProGlas, which comprises public figures including intellectuals and actors advocating for a fair voting process.

In the election, Serbia Against Violence came in second with 23.56 percent of the vote, while the Socialist Party of Serbia secured the third position with 6.56 percent.

Another opposition politician, Radomir Lazovic, has called on the international community "not to stay silent" and urged the formation of a commission to investigate the irregularities and pressure authorities to hold a new, free, and fair election.

After the speeches, participants marched towards the headquarters of the state electoral commission, then proceeded to Serbia's Constitutional Court, which will ultimately rule on electoral complaints.

Protesters expressed their discontent with the current situation. Rajko Dimitrijevic, a protester from Belgrade, stated that he joined the rally because he felt "humiliation" due to the perceived manipulation of the people's will. Ivana Grobic, also from Belgrade, joined the protest in the hopes of a better future and for the country's institutions to fulfill their responsibilities.

The opposition has called for an international investigation into the election following reports from global watchdogs that highlighted various irregularities, such as vote-buying and ballot box stuffing. Local election monitors also alleged that voters from Serbia and neighboring countries were transported to Belgrade to cast fraudulent ballots.

Symbolically held in a central area of Belgrade that was once the site of demonstrations against former strongman Slobodan Milosevic's undemocratic policies in the 1990s, the rally has drawn attention to the increasing concerns over President Vucic's consolidation of power since taking office in 2012.

President Vucic has maintained that the elections were fair and his party rightfully won. He accused the opposition of inciting violence during the protests with the aim of overthrowing the government, while opposition leaders have denied these claims.

Notably, Serbia, despite its formal pursuit of EU membership, has maintained close ties with Moscow, refusing to join Western sanctions imposed on Russia following the Ukrainian conflict. Russian officials have expressed support for President Vucic and endorsed his assertions that the elections were conducted freely and fairly.