The Czech Republic could be forced to return EU funds after preliminary investigations found Prime Minister Andrej Babis guilty of breaking conflict-of-interest rules, the Financial Times of London reported, citing Czech newspaper Hospodarske Noviny.

An audit by the European Commission found that Babis stayed connected to his businesses for more than two years after taking office. The billionaire-turned-politician tweeted that he received the preliminary investigation results and "strongly rejects" the findings, according to the report.

"The Czech Republic will not have to return any subsidies. There is no reason to do so because I do not violate either Czech or EU rules on conflict of interest," Babis reportedly tweeted.

Babis founded AGROFERT a.s., a conglomerate with businesses ranging from agriculture to media, and is said to have relinquished control of his former businesses before taking up office as finance minister in 2014.

The country's finance ministry said it will keep investigation details confidential until a final ruling is reached, but said it is prepared for the worst. "Of course, in the event that a certain expenditure is ineligible, the Czech Republic has the tools to recover it from the beneficiary," the ministry told the FT.

Meanwhile, a number of opposition parties are pushing for a discussion on the matter in the week of June 3, and the ruling coalition comprising Babis's Ano party and the Social Democrats could face a vote of no confidence at parliament, according to the report.