World heavyweight champion Tyson Fury will be stripped of his WBO belt unless he responds to a notice from its chairman in the next 10 days.
The 28-year-old Briton, who holds both WBO and WBA titles, withdrew from October's rematch with Wladimir Klitschko because of mental health issues.
A notice posted on the governing body's website, addressed to Fury, read: "Taking all of the previous under consideration, the WBO Championship Committee decided that you have 10 calendar days, final and non–extendable, to show cause why your title should not be vacated due to inactivity, breach of contract and performance-enhancing drugs and stimulants."
The boxer's uncle and trainer Peter Fury said on Sunday that his nephew, who said he was taking cocaine to help deal with depression, "will resume his career".