TEHRAN, Iran (AP) — Iran's nuclear chief says his country is designing a new atomic research reactor in another snub of international efforts to curb the Islamic Republic's nuclear ambitions.

State TV's website quotes Vice President Ali Akbar Salehi as saying Wednesday the new reactor will be more powerful than the aging, 5-megawatt U.S.-made research reactor operating in Tehran that is used to make radioactive isotopes for medical purposes. He says Iran eventually plans to build four such reactors.

Iran's first energy-producing reactor is scheduled to begin operations this summer.

Last week, the U.N. imposed sanctions over Iran's refusal to halt uranium enrichment, a process that can be used to fuel nuclear power plants or make nuclear weapons.