In his announcement, President Hassan Rouhani did not say whether the centrifuges, which are at its nuclear facility in Fordo, would be used to produce enriched uranium.
The centrifuges would be injected with the uranium gas as of Wednesday, Rouhani said.
His remarks, carried live on Iranian state television, came a day after Tehran’s nuclear program chief said the country had doubled the number of advanced IR-6 centrifuges in operation.