Andras Kadar’s comments came amid a government campaign targeting non-governmental organisations (NGOs) that has seen police raid offices and homes.
The Hungarian Helsinki Committee chairman warned the government of Hungarian prime minister Viktor Orban aimed to “weaken” human rights NGOs it considered a threat.
His warning came just after Mr Orban’s Fidesz party reinforced its position as Hungary’s dominant political force by emerging triumphant in local elections, while at the same time increasing concerns in the West of an erosion of democratic principles in the country.
Last month it emerged prosecutors and police have a “blacklist” of 13 NGOs involved in upholding civil and human rights.
Since then police investigating the alleged “fraudulent misuse of funds” have raided NGO offices and the homes of selected members of staff.
Mr Kadar said: “The charges are groundless, but now it would be very difficult for the government to let this go.”
The Hungarian authorities have focused their attention on NGOs receiving charitable funding from a foundation called the Norwegian Fund, claiming the money is being used improperly for political purposes and promoting foreign interests.
“We’re not dealing with civil society members but paid political activists who are trying to help foreign interests here,” Mr Orban said in a speech.
He added: “We don’t like it [when somebody] talks about respect for the law but when it comes to his own financial affairs calls for exceptional procedures, saying that’s not Hungarian money.”
Mr Orban’s accusation that NGO staff were foreign agents mirrored the words of Russian president Vladimir Putin, who has instigated a crackdown on foreign-funded organisations which has been seen as an assault on human rights and an attempt to silence dissent.
The Hungarian NGOs have rejected Mr Orban’s allegations and pledged to carry on with their work. “We are not vehicles of political parties or foreign interest. We are independent,” they said in a joint statement posted online. “We are working on a democratic, transparent and solid society. They are obviously trying to intimidate us. They are trying to suppress us. We will not quit.”
The Norwegian government has issued formal protests over Hungary’s actions and said it has no qualms over how the NGOs used the money. It also challenged Hungary’s right to investigate the accounts of NGOs using no Hungarian funding.
Mr Kadar said the Orban government has targeted the NGOs as part of a campaign to weaken or eradicate democratic checks and balances in Hungary, which some claim has already subjugated the law and the press.
He alleged NGOs had become the focus of government ire because they had helped inflict defeats on Hungary in international courts such as the European Court of Human Rights.
The situation has drawn international criticism, with Victoria Nuland – US assistant secretary of state for European affairs – accusing Mr Orban of “demonising civil society”.