Prime Minister Fumio Kishida's son has been given a strong warning over inappropriate photographs taken at the prime minister's residence during a family function last year, the top government spokesman said Thursday.

The caution given to Shotaro Kishida, who works as an executive secretary to his father, was disclosed by Chief Cabinet Secretary Hirokazu Matsuno after a weekly magazine reported that he posed for photographs with relatives at a staircase and other symbolically important parts of the residence in a manner seen as disrespectful.

Speaking at a regular news conference Thursday, Matsuno said the government is aware that the actions of the prime minister's eldest son "lacked appropriateness."