Asked whether Riyadh would "build a bomb itself" if Tehran seizes on Washington's withdrawal from the 2015 Iran deal to resume a nuclear weapons program, Jubeir said: "If Iran acquires nuclear capability we will do everything we can to do the same."

Oil-rich Saudi Arabia has long said it would match any Iranian weapons development, but Jubeir's renewed vow came after US President Donald Trump pulled the United States out of an accord designed to prevent Tehran's alleged quest for the bomb.

And it came amid growing tension between the Sunni kingdom and the Shiite Islamic republic over Iran's support for the Huthi rebels in Yemen, who have been firing rockets across the border.

Riyadh, which leads a regional coalition that intervened in Yemen's civil war to fight the Huthis, accuses Iran of supplying the militia with ballistic missiles.

"These missiles are Iranian manufactured and delivered to the Huthis. Such behavior is unacceptable. It violates UN Resolutions with regards to ballistic missiles. And the Iranians must be held accountable for this," Jubeir told CNN.

"We will find the right way and at the right time to respond to this," he warned. "We are trying to avoid at all costs direct military action with Iran, but Iran's behavior such as this cannot continue. This amounts to a declaration of war."