Veteran singer Masahiko Kondo has admitted to an extramarital affair and will be indefinitely suspended from activities as punishment, his management agency said in a statement released early Tuesday.

The 56-year-old singer, also known as Matchy, was "thoughtless" and "lacked awareness and a sense of responsibility" as an adult and married person, said Johnny & Associates Inc., one of Japan's most powerful talent agencies.

Kondo himself offered to step back from work, according to the agency, which has produced a large number of famous boy bands.

According to a report by the Shukan Bunshun weekly magazine that hit newsstands last week, Kondo had been in a relationship with a 31-year-old woman who runs a company making tailored suits.

Kondo is marking the 40th anniversary this year of his debut as a singer with the single "Sneaker Blues" in 1980. He was among the most popular male idols in Japan in the 1980s.

The indefinite suspension of entertainment activities is the "right" punishment for "the oldest" talent belonging to Johnny & Associates, the agency said, adding Kondo will reflect on his position as the agency's most senior talent during the period of suspension.