WASHINGTON -- US President Barack Obama and his Russian counterpart Vladimir Putin on Tuesday discussed the upcoming peace talks on Syria, and agreed to continue cooperation on Iran and Sochi Olympics.

In their phone conversation, the two leaders discussed the situation in Syria, including preparations for the so-called Geneva II conference and the ongoing efforts to remove and destroy Syria's chemical weapons, the White House said in a readout of the talks.

The peace conference was initiated by Washington and Moscow in May and will start Wednesday in the Swiss city of Montreux to seek the establishment of a transitional governing body in Syria to lead the country out of a protracted conflict that broke out in March 2011.

The United States and Russia have differed over approaches to the Syrian conflict and Iran's role in the talks. UN Secretary General Ban Ki-moon, under pressure from the US and other countries, withdrew his last-minute invite on Tuesday for Iran to join the talks.

Obama and Putin also discussed Monday the start of the implementation of an interim nuclear agreement reached on November 24 between Iran and the United States, Russia, Britain, France, China and Germany.

Iran has stopped producing 20 percent enriched uranium and begun diluting its existing stockpile, among others, in exchange for eased sanctions from major powers and the European Union.

Under their deal, Iran and the major powers will also work towards a comprehensive agreement through negotiations in the next six months.

In their phone talks, Obama and Putin also discussed "how best to advance shared US-Russian interests, including a safe and secure Sochi Olympics, for which the United States has offered its full assistance," the White House said.

In addition, the pair agreed to work on "concrete steps" to increase bilateral trade and investment, it added.