Ken Naganuma, who led Japan to their only Olympic medal in football and then helped build the country's professional league, died of pneumonia on Monday, officials said. He was 77.

Naganuma, who held a largely ceremonial position of top advisor to the Japan Football Association (JFA), died at a Tokyo hospital, association officials said, adding that his family planned to hold a private funeral.

Japanese players, including Celtic star Shunsuke Nakamura, mourned his death by wearing black armbands during Monday's World Cup qualifying victory over Oman in Yokohama.

Naganuma played for the national side as a striker when he was a university student and quickly rose to the rank of head coach in 1962. He was still only 34 when he coached Japan at the 1964 Tokyo Olympics, which symbolised Japan's rebirth as a major nation after the destruction of World War II.

He went on to lead the team at Mexico City in 1968, where Japan took home the bronze, their first and only medal in Olympic football. Japan beat France in the quarter-finals but lost to eventual gold medallists Hungary.

Naganuma helped establish the J-League in 1993. He was also one of the first people honoured at the nation's Soccer Hall of Fame.

"I was shocked to hear the sad news," JFA chairman Saburo Kawabuchi said in a statement. "When the J-League was launched, he provided full support, which has led to success in the league."

Japan has seen a boom of interest in football since the country co-hosted the 2002 FIFA World Cup™ with South Korea in 2002. Japan made their first-ever appearance in the FIFA World Cup in 1998.