"One of the examples of achievements in last 29 years [since the 1979 Islamic Revolution that deposed the U.S.-backed Shah] is the nuclear issue," Khamenei said on Tuesday, as cited by state-run radio.
"Those people who used to say Iran's nuclear activity must be dismantled are now saying we are ready to accept your advances, on condition that it will not continue indefinitely," he said.
He also praised Iranian President Mahmoud Ahmadinejad's role in the country's refusal to give in to Western pressure over the nuclear issue.
The head of the UN nuclear watchdog said on Friday that Iran had become more transparent about its nuclear program, but had failed to fully answer Western allegations that it was seeking to create a nuclear weapon.
"In the last four months we have made quite good progress in clarifying the outstanding issues," Mohamed ElBaradei, director of the International Atomic Energy Agency (IAEA), said in a statement accompanying a new report on Iran's nuclear activities.
Iranian chief nuclear negotiator Saeed Jalili hailed the IAEA report as yet more proof that Iran's nuclear research was peaceful.
Jalili said Iran would continue cooperation with the IAEA and strictly observe the provisions of the Non-Proliferation Treaty.
The diplomatic standoff between Iran and the West began almost six years ago over suspicions that Tehran was developing a nuclear weapons program. Tehran has always maintained it needs nuclear technology for peaceful purposes. Since then, two rounds of sanctions have been imposed - in December 2006 and March 2007.
The five permanent UN Security Council members and Germany agreed at talks in Berlin on January 22 on a draft for a third sanctions resolution against Iran, calling for travel bans and asset freezes.
The move came despite a U.S. intelligence report in late 2007 suggesting that Iran had not been engaged in attempts to create nuclear weapons since 2003.
The new draft resolution was officially introduced by France and Britain in the UN Security Council earlier on Friday, and council members are expected to vote on the resolution at some point next week.
The outcome of the vote will largely depend on the assessment of the new IAEA report.
