The doctor who treated Mo Farah with a controversial infusion has been summoned to give evidence to MPs.
The infusion of the legal supplement L-carnitine, given to Farah in 2014 before a major race, is being looked at by the US Anti-Doping Agency (Usada) to determine whether rules were broken.
Dr Robin Chakraverty carried out the treatment on the instruction of Farah's American coach Alberto Salazar.
He will appear before the Culture, Media and Sport Committee on 19 April.
MPs have also asked to speak with UK Athletics' head of endurance Barry Fudge as part of their ongoing investigation into doping in sport.
Fudge works closely with Farah and Dr John Rogers, a medic for the British athletics team who reportedly raised concerns about Salazar's methods.
Salazar has been under investigation by Usada and UK Anti-Doping (Ukad) since 2015, following claims of doping and unethical practices made in a BBC Panorama programme.
Both Salazar and Farah have strongly denied breaking any rules.