Moscow may shelve the delivery of the advanced S-300 air defense system to Iran as Russia seeks to turn a "new page" in its ties with the US.

Russia's Interfax news agency quoted a source familiar with the issue as saying on Tuesday that the Kremlin may freeze a controversial deal to supply Iran with the sophisticated missile system.

"Such a possibility is not excluded. The question must be decided at a political level, especially as the contract was worked out on a purely commercial basis," the unnamed source said.

The report was released on the same day Russian President Dmitry Medvedev said he predicts a "new page" in Russia-US relations under Barack Obama.

"The signals being received from the US president are completely positive," Medvedev said after meeting with high-ranking members of the US Senate in Moscow.

The Obama White House has pledged to mend its strained relations with the Kremlin, stressing that the two sides must find common approaches on a variety of issues, including Iran and its controversial nuclear program.

Tehran says the only aim of its nuclear program is the civilian applications of the technology. The US, Israel and their European allies -- Britain, France and Germany -- accuse the country of having military objectives in its pursuit of nuclear technology.

Despite Western doubts over the success of any military plan against Iran, Israel -- which terms Tehran as an "existential threat" -- has repeatedly threatened to take out Iranian nuclear infrastructure with aerial strikes.

Following an escalation in Israeli rhetoric, Iran has moved to upgrade its defenses and has reportedly opted to acquire the S-300 system -- which, according to Western experts, would rule out the possibility of an Israeli airstrike on Iranian nuclear sites.

"If Tehran obtained the S-300, it would be a game-changer in military thinking for tackling Iran," says long-time Pentagon advisor Dan Goure.

The S-300 surface-to-air missile system, which can track targets and fire at aircraft 120 km (75 miles) away, features high jamming immunity and is able to simultaneously engage up to 100 targets.

The Russian source added that while the contract had been signed in 2005 the delivery of the controversial system has yet to take place.

The delivery of the missiles is expected to ruffle feathers in the United States, which fears Iran is seeking an atom bomb and has long refused to take the military option against the country "off the table".

CS/MD/HGH