The Anonymous hackers' group briefly shut down company websites of billionaire Czech Finance Minister Andrej Babis's food and agriculture empire in protest at a law giving the state the power to close illegal gambling sites.
Babis, the country's second-richest man, founded a political movement that stormed to power in 2013. But his businesses have left him exposed to criticism of potential conflicts of interest, and hackers have now also taken aim at his companies.
Lupa.cz, a private news agency, reported that Czech hackers from Anonymous shut down the websites of Babis's holding company Agrofert and bakery group Penam for a short period on Monday evening.
An Agrofert spokesman confirmed on Tuesday the websites were down for around five minutes.
The hacker group has threatened more website attacks against Agrofert and lawmakers and called for the cancellation of the new law that places greater restrictions on gambling and allows the ministry to close sites operating illegally in the Czech Republic.
"The Finance Ministry led by Andrej Babis gets almost limitless power to censor the internet. It is time to move against it," Anonymous said in a video posted on Youtube on July 18 describing what it called Operation Blockade.
The hackers also demanded the end of a planned online system for monitoring retail sales that the finance ministry is launching at the end of the year.
Babis has put new emphasis on battling tax fraud and improving collection to boost state coffers since becoming finance minister in 2014. The gambling laws and online sales reporting system are part of that effort.
He told Reuters on Tuesday he had met before with a representative of Anonymous and added he would file a criminal complaint over the attacks.
"We only want to apply rules used by 18 (European Union) countries already, nobody wants to censor the internet. It is aimed against gambling companies that do not pay taxes," Babis said.