Lagos - Nigeria's ailing President Muhammadu Buhari who has been away in London for almost three months has become the subject of a sports betting game in his homeland. A popular sports gaming site, NaijaBet.com, is asking those interested to stake their money on when Buhari who left Nigeria on May 7 on his latest medical trip to the British capital, would return. The company usually focusses on English Premiership, Champions League and other sporting events, but recently launched the 'Buhari to Return' game:"You can bet on if he will return on the 2nd week of August or the 4th"The 74-year-old Buhari first sought treatment in London in June last year for what presidency officials said was a persistent inner ear infection, returning in six months for check-ups that were later said to be "a long period of treatment". Buhari himself admitted on his return to Abuja in March that he had not been that ill before. Despite Vice President Yemi Osinbajo's acting on his behalf, Buhari's protracted absence has sparked intense public debate in Nigeria. Last month, both members of the ruling party and the opposition went to see him in London and even took pictures with him in London to douse public anxiety. The health of Nigerian leaders has often been a contentious issue. Buhari, a former military ruler in the 1980s, was dogged by speculation about his health even before the election win in 2015 that brought him to power. During that campaign, the then-ruling party claimed he was seriously ill with prostate cancer and even put out advertisements insinuating he would die in office. He rejected the claims as unfounded. In 2010, Nigeria was plunged into months of political turmoil after president Umaru Musa Yar'Adua died in office following months of treatment in Saudi Arabia.