PITTSBURGH (Reuters) - Russian President Dmitry Medvedev said on Friday that if Iran does not cooperate at an October 1 meeting with world powers, then other methods should be used to deal with Tehran’s nuclear program.

Medvedev made the comment in answering a question about whether a new round of U.N. sanctions might be in order after U.S. President Barack Obama’s announcement that Iran has a second nuclear facility it had been keeping secret.

“I have said we should create a system of incentives for Iran,” Medvedev said. “If they do not work, cooperation does not work, other mechanisms of which I spoke should be used.”

Medvedev said the new revelations were a “cause of concern” to all participants at a Group of 20 summit in Pittsburgh, including Russia. Negotiators from six major powers plus Iran will meet on October 1 in Geneva to discuss their differences.

Russia, like China, has been reluctant in the past to toughen sanctions against Iran.

Medvedev’s comments at the end of the G20 summit showed signs of Russian impatience that Iran violated several demands by the U.N. Security Council for it to halt all uranium enrichment activities.

The International Atomic Energy Agency, the U.N. nuclear watchdog, should launch an immediate investigation, he said in a statement.

Western countries fear Iran is working to make nuclear weapons, while Tehran insists its program is designed solely to generate electricity.

DEADLINE FOR IRAN

Medvedev said the October 1 meeting “gives Iran a chance to demonstrate that it is also committed to talks to solve this issue.”

“We hope that ... Iran will provide convincing proof of its commitment to develop a nuclear energy sector exclusively for peaceful purposes,” he said.

The statement -- in particular the focus on the October 1 deadline -- was firmer than previous remarks by Moscow, which have largely stressed the need for dialogue with Iran.

Medvedev repeated that Russia was committed to talks on ending the standoff but made no mention of sanctions.

Obama and Medvedev agreed on Wednesday that serious additional sanctions had to be considered if Iran did not respond to proposals to end the nuclear standoff.

Moscow has so far supported U.N. Security Council statements condemning Iran’s nuclear ambitions while rejecting the idea of tougher sanctions, for example those targeted against the country’s energy sector.

A U.S. official said Washington had been monitoring the construction of the plant for several years.

A source in the Russian delegation said it appeared that “one of the Western secret services discovered the new plant and Iran came out with (the) disclosure to ease tough Western reaction.”