Updated

An 18-year-old Mongolian wrestler who collapsed after complaining of neck pain remains unconscious following brain surgery, sumo officials said on Thursday.

Kengo, a lower-division wrestler, was taken to hospital earlier in the day after collapsing at a bath house following a sparring bout, according to the Japan Sumo Association (JSA).

Doctors removed a hematoma (accumulation of blood) from the wrestler's head in a four-hour operation.

"The doctors indicated there could be further complications and painted a bleak picture," his gym chief Nishonoseki told reporters.