“The right to enrichment within the framework of the NPT and under the surveillance of the IAEA is an absolute right,” government spokesman Gholam Hossein Elham told reporters.

“This right and its implementation must be guaranteed. This is not something on which we can back down, whether for research or industrial purposes. This is not something on which we can negotiate or back down,” he said.

Britain, France and Germany are drawing up a proposal aimed to persuading Iran to halt fuel cycle work, which Washington and its allies say hides an effort to build a nuclear bomb.

The European package could include trade, technology and security benefits if Tehran stops enriching uranium, a process which can be extended to make weapons. If Tehran does not accept the deal, sanctions could follow.

Iran says it only wants to make reactor fuel, a right enshrined by the Non-Proliferation Treaty and overseen by the UN’s International Atomic Energy Agency.

“Nuclear technology is a right that nobody can challenge, and all Iranians are unanimous in claiming this right,” Elham said.