Iran has asked the International Atomic Energy Agency for permission to exempt at least two dozen centrifuges from a freeze on its nuclear development program.
The request on Wednesday is a partial reversal of the Islamic republic's agreement with the European Union, implemented Monday, to suspend the program. The appeal is reported to have evoked a negative response from European representatives.
Iran says it wants to use the centrifuges for peaceful research and development.
The request comes just one day before the 35-member board of the energy watchdog agency is to meet in Vienna to discuss Iran's compliance with IAEA restrictions. A finding of non-compliance could lead to UN Security Council sanctions.
The United States has accused Iran of developing atomic weapons, a charge Iran has consistently denied.