Iran has proclaimed new advances in its nuclear programme.
President Mahmoud Ahmadinejad appeared on state television to announce the production of “domestically made” reactor fuel for the first time.
He also said Iran would be able to enrich uranium faster.
It comes at a time of increased tension between Iran and Western powers over Tehran’s nuclear activities.
The US State Department dismissed the announcement as “not terribly impressive” and “overhyped.”
Russian Foreign Minister Sergei Lavrov urged Iran to continue talks with the UN’s International Atomic Energy Agency.
“We believe it is absolutely necessary to avoid any steps which might undermine cooperation between the IAEA and Iran,” he said.
Iran’s pursuit of its nuclear programme derailed negotiations with the five permanent members of the UN Security Council and Germany over a year ago.
A spokeswoman for EU foreign policy chief Catherine Ashton said the Iranian government has written, expressing readiness to hold new talks “in a constructive way”.
Iran insists its programme is for civilian purposes, but the West fears it may try to build a nuclear weapon.