A Serbian opposition leader has been released from detention after suffering what he alleges was a terrifying ordeal in which Belgrade secret services “beat me, tortured, humiliated me and threatened to kill me and my family”. Nikola Sandulović, the leader of the Serbian Republican party, said he was taken from his home 10 days ago and subjected to violent abuse for more than six hours by the intelligence service. As a result, his lawyers say, he remains paralysed on his left side and is suffering nerve damage. Speaking for the first time since his release, Sandulović said in a statement on Wednesday: “I was kidnapped by members of the Serbian secret police, who beat me, tortured, humiliated me and threatened to kill me and my family for more than six hours, endangering not only my health but also my life. “All this because of my political expression and the act of laying flowers on the grave of a murdered seven-year-old girl, who belonged to the Jashari family.” Sandulović has been accused of breaching laws prohibiting the incitement of national, racial and religious hatred. The charges were levelled after he apologised for crimes committed by Serbs against ethnic Albanians during the Kosovan war of independence in 1998 and 1999. He has been heavily criticised by pro-government media for reposting a video of a visit he made to the grave of Adem Jashari, a founder of the Kosovo Liberation Army who was killed by Serbian police in 1998 along with 57 members of his family. Sandulović said that after the alleged attack the secret service took him home. Immediately after, he said, the police arrived with an order to take him to prison. Instead, he said, he was taken to the emergency centre as his “condition was critical”. Giving a first-hand account of the incident, which has raised fresh fears about democracy in Serbia, the opposition politician said he was then transferred to a prison hospital and sentenced at the same time to “the unjust detention of 30 days” which he said put his life in danger. The Security Intelligence Agency (BIA) has acknowledged questioning Sandulović but, in a statement to the Financial Times, said he was “not subjected to any unlawful use of physical force or freedom and rights violations”. BIA only wanted to “elucidate the context of Sandulović’s unlawful actions, which the competent prosecutor classified as a criminal offence … inciting national, racial and religious hatred and intolerance”. The service denied reports of its agents beating him up, saying the allegations were aimed at destabilising the country. The Serbian government has been approached for comment. Sandulović’s release came as opposition parties in Serbia were buoyed by a discussion in the European parliament in Strasbourg of allegations that the recent elections were rigged in favour of President Aleksandar Vučić’s SNS, an accusation Vučić denies. Marinika Tepić of the opposition Serbia Against Violence (SPN) coalition said on Tuesday: “We have achieved our objective, and today Europe and the whole world know that we caught the thieves in the act.”