A mayor in western Japan, who has taken a hard-line stance toward news organizations he considers "biased," refused to answer questions from a reporter on Thursday, telling him "I'll kill you" before walking away.

Takeshi Imamura, the 45-year-old mayor of Nishinomiya in Hyogo Prefecture, made the remark when the reporter from the Yomiuri Shimbun national newspaper approached him at the city hall to confirm his intention not to seek re-election, city officials said.

The reporter was trying to double-check after the mayor said during a ceremony marking the first working day of the year, held at the city hall earlier in the day, that he would not run in the mayoral election slated in April.

Imamura, a former Nishinomiya city assembly member, is in his first four-year term as mayor after winning the 2014 election.

He has caused controversy over a policy he temporarily adopted of not answering questions from "biased" news media outlets, and making comments ridiculing a female city assembly member who criticized him.

"We will deal with this matter appropriately after confirming what happened," said a spokesman for the newspaper.