Brussels has criticised Slovenia's prime minister for "insulting" a journalist by claiming she had been "instructed not to tell the truth".
Janez Jansa made the remarks over a Politico Europe article that is entitled "Inside Slovenia’s war on the media". It claimed that Jansa's alleged attacks on journalists had created a climate of fear in the country.
He claimed the journalist had been instructed to lie and had quoted unknown sources from the extreme left.
Stephen Brown, Politico Europe's editor in chief, said its "independent, unbiased journalism speaks for itself" and stood by the article and journalist.
Eric Mamer, the chief spokesman for the European Commission, said the EU "does not accept and condemns the insulting remarks towards journalists, including in this case".
Reports Without Borders has been raising concerns about Jansa for months, accusing him of waging a "hate campaign" against journalists.
"We would welcome any delegation from any institution that would try to prove that the major media are under government control," Jansa tweeted on Thursday evening.
"We would probably only need a visit of a few hours (...) to clarify matters," he added, expressing doubts that the European Commission had taken a direct stance on the issue.
In its rule of law report last year, the EU's executive arm noted that journalists in Slovenia are "frequently victims of online harassment or threats, which are rarely punished by the justice system".
Reporters Without Borders has urged the EU to remind Jansa that press freedom is a key principle of the 27-nation bloc.
Slovenia is due to take over the EU's rotating six-month presidency in July.
In January, the European Commission warned Slovenia against any attempt to "pressure" the media, following a decision in Ljubljana to suspend funding for the national news agency. The Slovenian government finally authorised the grants after being reprimanded by Brussels.