MOSCOW, September 26 (RIA Novosti) - Iran's president has rejected Western accusations that his country's nuclear program runs counter to international agreements, and insisted on the legality of the newly revealed second uranium enrichment site.

Earlier this week Iran told the International Atomic Energy Agency (IAEA) about a partially-built second uranium enrichment plant. The revelation prompted condemnation from Western powers, which suspect Iran of pursuing a covert atomic weapons program.

Speaking to journalists in New York, President Mahmoud Ahmadinejad said the facility operates in line with UN nuclear regulations.

"According to the IAEA rules, countries must inform the Agency six months ahead of the gas injection in their uranium enrichment plants. We have done it 18 months ahead, and this should be appreciated not condemned," Iranian state channel Press TV quoted him as saying.

The new plant is being built near Qom, around 160 km (100 miles) southwest of Tehran.

Russia, which has traditionally supported Iran in the long-running dispute over its nuclear program, voiced concern on Friday over the second enrichment site, and urged the country to provide reassurances over its nuclear program.

President Dmitry Medvedev said in a statement circulated at a G20 economic summit in Pittsburgh that the fact that Iran has been building a uranium facility for several years without informing the UN nuclear watchdog is a "source of serious concern."

"The construction of a new uranium enrichment facility runs counter to the UN Security Council's repeated demands that Iran freeze its enrichment activities," Medvedev said.

He urged the country to take steps to prove that its nuclear program is peaceful before a meeting with six world powers in Geneva on October 1.