Romanian far-right populist Calin Georgescu has been barred from participating in May's presidential election rerun by the country's Central Electoral Bureau (BEC), triggering clashes between his supporters and police.

Last year, Romania's constitutional court annulled November's first round of the vote - in which he came first - after intelligence revealed Russia had been involved in 800 TikTok accounts backing him.

The BEC rejected his candidacy on Sunday, saying it "doesn't meet the conditions of legality", as he "violated the very obligation to defend democracy".

Georgescu called that decision a "direct blow" to democracy. He now has 24 hours from Sunday's verdict to submit an official appeal to the top court, which should issue a ruling within 72 hours.

In a social media post, Georgescu called the ban a "direct blow to the heart of democracy worldwide".

Tear gas was fired at supporters of the presidential hopeful as violence broke out between them and police while they gathered in their thousands outside the offices of the BEC in the capital Bucharest.

The BBC saw at least one car turned over, and the windows of neighbouring bars smashed. At least four people were detained.

While many protesters left the scene, several hundred people remained and continued to fight with riot police, who brought in reinforcements and attempted to cordon off the area.

On 26 February, Georgescu was arrested on his way to register as a candidate in the summer election, prompting tens of thousands of Romanians to march on Bucharest's streets in protest.

He was charged with attempting to overthrow constitutional order and membership of a neo-fascist organisation. He has denied all wrongdoing.

The 62-year-old independent came from nowhere to win the first round of last year's election, the results of which were annulled just days before the second round of voting.

One key to his sudden popularity was his promise to "restore Romania's dignity" and end subservience to the international organisations it belongs to, including Nato and the EU.

Before last year's annulment, the pro-Russian politician told the BBC he would end all support for Ukraine if he was elected.

Georgescu has also seen some support from the Trump administration.

Last month, US Vice-President JD Vance accused Romania of annulling the elections based on the "flimsy suspicions" of Romanian intelligence and pressure from its neighbours.

Meanwhile, Romanian Foreign Minister Emil Hurezeanu accused Elon Musk of a "form of interference" in Romania's elections, after the billionaire posted several messages of support for Georgescu.