Iran is facing renewed pressure from world powers after a new United Nations report said Iran has begun installing advanced centrifuges at its main uranium-enrichment plant.
The United States said the Iranian move would be a “provocative step,” while Britain called it a “serious concern.”
Iranian regional rival Israel said Iran was now “closer than ever” to obtaining enriched material for a nuclear bomb.
The UN’s nuclear watchdog, the International Atomic Energy Agency (IAEA), earlier reported Iran has begun installing advanced centrifuges at its Natanz nuclear site. These would enable the Islamic republic to speed up uranium enrichment.
Iran denies any effort to make a nuclear weapon.
Iran is due to meet next week in Kazakhstan with representatives of six major powers – Britain, China, France, Germany, Russia, and the United States -- to discuss the nuclear issue.
The IAEA report said that on February 6 inspectors observed that IR-2m centrifuges were being installed at the Natanz plant. It said 180 centrifuges and empty centrifuge casings had been set up but were not yet operating.
The report said it was “the first time that centrifuges more advanced than the IR-1 have been installed" at the plant in central Iran.
A nuclear weapon can be created using highly enriched uranium, which the new centrifuges would enable Iran to produce at a faster rate.
Iran says it is refining uranium only for peaceful purposes.
Iran’s envoy to the IAEA, Ali Asghar Soltanieh, told Iranian media the UN report showed "no evidence of diversion of material and nuclear activities towards military purposes."
In Washington, U.S. State Department spokeswoman Victoria Nuland said installation of advanced centrifuges would mark a “further escalation” by Iran.
“The fact remains that the installation of new advanced centrifuges would be a further escalation and a continuing violation of Iran’s obligations under the relevant UN Security Council resolutions and IAEA board resolutions," Nuland said. "So it would mark yet another provocative step.”
At the White House, President Barack Obama’s spokesman James Carney said Tehran will face more isolation if it continues to ignore international demands to halt enrichment.
“Iran has a choice," Carney told reporters. "If it fails to address the concerns of the international community it will face more pressure and become increasingly isolated. The burden of sanctions could be eased, but the onus is on Iran to turn its stated readiness to negotiate into tangible action.”
Carney said Washington hopes Tehran will come ready for “substantive” discussions at the February 26 talks with six major powers in Almaty, Kazakhstan.
The IAEA report said Iran has continued to enrich uranium to a purity level of 20 percent – a level closer to what is necessary for weapons-grade material.
But it said Iran had converted some of this material into fuel for a research reactor in Natanz.
It said Iran is believed to now have 167 kilograms in its stockpile of 20 percent uranium.
Experts say about 250 kilograms of 20 percent enriched uranium would be needed to build one bomb.
Four rounds of United Nations Security Council sanctions have failed to persuade Iran to halt enrichment. Since sanctions were imposed, Iran has in fact expanded such activity, saying it has the right under the Nuclear Nonproliferation Treaty.
With reporting from Reuters and AFP