A Japanese reporter on Thursday pleaded not guilty to charges of defaming South Korea's president by reporting rumors that she was absent for seven hours during a ferry disaster in April because she was with a man.

The indictment of Tatsuya Kato of Japan's Sankei Shimbun newspaper has raised questions about South Korea's press freedoms. Critics accuse South Korean President Park Geun-hye's conservative government of clamping down on journalists in an attempt to control her image. It also comes at a low point for Japanese-Korean relations due to a territorial dispute over a small island and conflicts over wartime history.

Kato was indicted over his Aug. 3 article about Park's whereabouts on the day the Sewol ferry sank and killed more than 300 passengers, mostly teenagers on a school trip. The article repeated rumors in South Korean media and the financial industry about a relationship between Park and a former aide who was said to be married at the time.

Park and her government have been criticized for the botched rescue operation on the ferry, and South Korean media had questioned whether she was unaccounted for on the day of the disaster.

Park's office has denied that she was with the former aide.

The lawyers representing Kato, who has been banned from leaving the country but is not under arrest, said in court that the article was in the public interest, according to court spokesman Kim Dae-hyun.

"The article (I wrote) was to let the Japanese people know about South Koreans' view on President Park," Japan's Kyodo News agency quoted Kato as saying.

The case has opened a debate on freedom of expression in South Korea, where the charge of defaming the president has been rarely used. If convicted, Kato could face a maximum prison sentence of seven years or a fine of 50 million won ($45,500).

Japan's Foreign Ministry last month summoned a South Korean diplomat in Tokyo to protest the indictment. The Seoul Foreign Correspondents' Club in October issued an open letter to prosecutor general Kim Jin-tae, expressing concern that Kato's indictment could have an "adverse impact" for the country's media. Moon Jae-in, an opposition lawmaker and Park's main rival in the 2012 presidential elections, told reporters on Tuesday that the prosecution's decision to indict Kato was an "embarrassment."

Until the late 1980s, South Korea was ruled by a succession of military dictators, including Park's father, Park Chung-hee, who suppressed journalists and dissenters.

Kato's next court date was set for Dec. 15.