BOSTON, January 20 (Reuters): Conor McGregor's reign as UFC lightweight champion looks to be over after the organisation's president Dana White said on Friday that American Tony Ferguson and Russian Khabib Nurmagomedov will fight for the undisputed title on April 7. The UFC had previously announced that interim lightweight title holder Ferguson would meet Nurmagomedov at UFC 223 in Brooklyn, and the winner of that fight will now become the undisputed champion, White told a news conference on Friday. However the UFC chief did not say that Irishman McGregor had already been stripped of his belt, despite repeated questions from the media. By far the sport's most high-profile athlete, McGregor rose through the UFC ranks, knocking out Jose Aldo in 13 seconds to be crowned featherweight champion in December 2015 and adding the lightweight belt less than a year later. But the 29-year-old's time as a two-weight champion was short-lived as he was soon stripped of the featherweight belt. McGregor has not mounted a title defence in either weight class. His only outing since beating Eddie Alvarez for the lightweight belt in November 2016 was a lucrative boxing match in August last year against the undefeated Floyd Mayweather, which the Irishman lost in the 10th round.