LONDON — They’re track-and-field legends who have competed around the world, at events including the Olympics and the London Marathon. They have run in stadiums packed with thousands of screaming fans, racing for medals and the glory of being crowned No. 1.

But an ugly feud between Mo Farah, a Somalia-born British runner, and his former childhood hero, Haile Gebrselassie, an Ethiopian runner who set 27 world records over his career, spilled into public this week.

According to news reports and the athletes’ public statements, the dispute revolves around claims of a theft, unpaid bills and an unprovoked violent attack. It all comes as Mr. Farah, the most successful British track athlete in history, is preparing to run the London Marathon on Sunday.

The public became aware of the simmering dispute during the final moments of a news conference in London on Wednesday, where Mr. Farah lit the fuse. As the event was wrapping up, he used his final few minutes onstage to reveal that although his marathon training had gone according to plan, he had been the victim of theft in a hotel outside of Addis Ababa, Ethiopia, where he had spent the past few months training.