Japan Sumo Association Chairman Musashigawa said Thursday he is back to work after undergoing surgery for stomach cancer, but association sources said he is expected to resign this month over betting scandals and the ancient sport's yakuza ties.

"From now on, all the stablemasters and ranking wrestlers will work together for reform and strive to rebuild the association to overcome the difficulties," Musashigawa said after an extraordinary association meeting of the sumo board.

But the ex-grand champion refrained from directly answering questions about the leaked resignation rumors.

Former Tokyo High Prosecutor's Office chief Hiroshi Murayama has been serving as acting chairman of the sumo governing body because Musashigawa was put on probation after Miyabiyama, an ozeki from his stable, admitted gambling on professional baseball, which is banned.

The Education, Culture, Sports and Science and Technology Ministry, which oversees the sumo association, has requested that Musashigawa be replaced, the sources said.