Prince Turki al-Faisal told the BBC that Saudi Arabia would then seek the same right, as would other nations.
Six world powers are negotiating an agreement aimed at limiting Iran's nuclear activity but not ending it.
Critics have argued this would trigger a nuclear arms race in the region spurred on by Saudi-Iran rivalry.
"I've always said whatever comes out of these talks, we will want the same," said the prince, Saudi Arabia's former intelligence chief.
"So if Iran has the ability to enrich uranium to whatever level, it's not just Saudi Arabia that's going to ask for that.
"The whole world will be an open door to go that route without any inhibition, and that's my main objection to this P5+1 [the six world powers] process." With a late March deadline for an Iran deal approaching, Saudi Arabia last week signed a nuclear co-operation agreement with South Korea that included a plan to study the feasibility of building two nuclear reactors in the kingdom.
Riyadh has also signed nuclear co-operation agreements with China, France and Argentina, and intends to construct 16 nuclear power reactors over the next 20 years. (+ BBC video) » | Barbara Plett Usher | BBC News, Riyadh | Monday, March 16, 2015
