South Korean prosecutors said Tuesday they have extended a travel ban on a Japanese journalist accused of defaming President Park Geun-hye by reporting false rumors about her whereabouts on the day of April's deadly ferry sinking.

Tatsuya Kato, former head of the Seoul bureau of Japan's conservative Sankei Shimbun newspaper, was indicted Wednesday on defamation charges for reporting that Park and an unidentified man had an alleged secret meeting on April 16, citing rumors circulated in South Korea's financial community. 

The Seoul Central District Prosecutors' Office said it has extended for three months the travel ban on Kato, who has been banned from leaving the country since Aug. 7.

The ban is likely to be extended further since it is not usually lifted until the trial ends, it added.

On Aug. 3, Kato wrote an article online about Park's whereabouts on April 16 when the Sewol ferry sank off the southwest coast, killing more than 300 people, mostly high school students on a school trip. 

He cited a column carried by the Chosun Ilbo in mid-July, in which South Korea's largest-circulation newspaper said Park's whereabouts were unknown for seven hours, a development it said caused rumors that she met a man at an undisclosed location.

A local civic group filed a complaint against Kato, and prosecutors have summoned him three times for questioning, concluding that the newspaper's move to raise questions about Park's whereabouts are groundless.

The presidential office refuted the newspaper's claim, saying that Park "was inside the presidential compound."

The indictment has sparked fierce backlash from Japan as Tokyo claims that the move has discriminated against foreign media and suppressed freedom of speech.

Seoul's foreign ministry said Tuesday that Japan should be coolheaded over the issue as it is a matter of law enforcement.

"I believe that Japanese people need to remain coolheaded as the indictment was made in accordance with due legal procedures in response to the civic group's complaint," Noh Kwang-il, spokesman at the foreign ministry, told a regular press briefing.

"As I think that this issue is related to legal procedures, not diplomatic affairs, it is not proper that Japanese government officials make unnecessary comments." (Yonhap)