WARSAW (Reuters) - The US ambassador to Poland on Thursday criticised the country's broadcast regulator for questioning the ownership structure of US company TVN Style.

TVN Style is owned by U.S.-based Warner Bros. Discovery, whose other channels - including news channel TVN24 - have previously experienced delays to licence renewals in Poland.

The Polish National Broadcasting Council (KRRiT) said on Wednesday that a vote on TVN Style's licence renewal was inconclusive.

"According to the chairman of KRRiT, granting a licence for the TVN Style program could involve breaking Polish and European law. For this reason, the company's capital structure will be subject to a detailed analysis by independent experts," it said.

"Anything that undermines faith in the predictability of the investment climate in Poland, such as yesterday's statement by KRRiT questioning the legitimacy of an American company operating in Poland, undermines our common values, bilateral interests and the rule of law," US ambassador to Poland Mark Brzezinski said on X on Thursday.

TVN said in a statement that its ownership structure raises no doubts, as confirmed by court judgments, numerous legal opinions and previous decisions of KRRiT granting licences to its channels.

"The failure to extend the licence for TVN Style and the comments of the head of KRRiT are another unlawful attack on the American investor and the values that unite our countries," it said in a statement on Thursday.

TVN is owned by Warner Bros. Discovery via a firm registered in the European Union to adhere to the requirements of a ban on non-European firms owning more than 49% of Polish media.

TVN24 was criticised by Poland's former nationalist Law and Justice (PiS) government which alleged that it distorted public debate by representing foreign interests.

PiS lost power last year, but some of KRRiT members were nominated by the previous parliament where the PiS party had a majority in the lower house.

On Thursday, parliament members of the country's ruling coalition submitted a preliminary motion to bring the head of KRRiT before the State Tribunal - an arm of the judiciary whose main task is to enforce compliance with the constitution by the highest state bodies and officials.

The members of parliament alleged that the head of KRRiT, Maciej Swirski, has blocked financing for public media and licences for private broadcasters, including TVN24, among others.

Swirski was not immediately available for comment.

(Reporting by Anna Koper; Editing by Jane Merriman)