News of Iran's capabilities follows the recent election of President Masoud Pezeshkian, who has said his goal is to "get Iran out of its isolation," and who favors reviving the 2015 nuclear deal between Iran and global powers.

Blinken said that "what we've seen in the last weeks and months is an Iran that's actually moving forward" with its nuclear program.

The United States unilaterally withdrew in 2018 from the Iran nuclear deal, which was designed to regulate Iran's atomic activities in exchange for the lifting of international sanctions.

Speaking at a security forum in Colorado, Blinken blamed the collapse of the nuclear deal for the acceleration in Iran's capabilities.

"Instead of being at least a year away from having the breakout capacity of producing fissile material for a nuclear weapon, (Iran) is now probably one or two weeks away from doing that," Blinken said.

He added that Iran had not yet developed a nuclear weapon.

Iran's acting Foreign Minister Ali Bagheri told CNN earlier this week that his country remained committed to the deal, known as the JCPOA.

"We are still a member of JCPOA. America has not yet been able to return to the JCPOA, so the goal we are pursuing is the revival of the 2015 agreement," he said. "We are not looking for a new agreement."

Bagheri added that: "Neither I nor anyone else in Iran has not talked and will not talk about a new agreement. We have an agreement (signed) in 2015."

Blinken made the statement just days after reports emerged that the US Secret Service increased security for Republican presidential nominee Donald Trump weeks ago, after authorities learned of an alleged Iranian plot to kill him.