"Head of the Chechen Republic Ramzan Kadyrov is undergoing a course of medical treatment", Alvi Karimov explained.
The official noted that according to the republic's constitution, the prime minister takes on the role as head of Chechnya if the current one is temporarily unwell or on vacation.
"This is a standard practice ... and it is employed in all [Russian territorial] subjects", he said.
Karimov added that Huchiev had acted as interim head in the past when Kadyrov was on vacation.