Tougher punitive measures over the last year and possible sabotage aimed at slowing Iran's nuclear drive could help buy more time for diplomacy and reduce the risk of the long-running row escalating into a military conflict, at least for now.

Signaling determination to keep up the pressure, US Secretary of State Hillary Clinton said the Obama administration may propose new unilateral sanctions on Iran, one of the world's largest oil exporters.

Also on January 19, Switzerland said it was tightening its sanctions with steps aimed at preventing it from being used by Tehran to get goods it could not buy elsewhere.

But the Islamic Republic's hard-line leaders, who use the nuclear dispute to rally nationalist support at home and distract from the country's economic problems, are showing no sign such measures will make them change course.

Ahmadinejad later told local TV in Yazd, the city where he made his speech, that if the other countries accepted that Iran has "become nuclear", the talks could reach a positive conclusion in the coming months.

"This process, I think, would take two or three months and would not have any result but for them to accept Iran's nuclear rights and they should stop their bad manners and stop their (sanctions) resolutions and start to expand cooperation with Iran", he said.