Russia's foreign minister says the next round of Syria talks expected to be held this weekend must not focus squarely on demands for Syrian President Bashar Assad's resignation.

Sergey Lavrov, speaking on a trip to Armenia on Monday, said some of the participants in the talks have kept pushing for Assad to step down, in what he described as a "simplistic approach."

The first round of Vienna talks on Oct. 30 left open the thorny question of when Assad might leave power.

Lavrov said the talks should focus on reaching consensus on who should represent the Syrian opposition and who should be considered extremists. He said the Organization of Islamic Cooperation and the Arab League should be invited to join the following round of Vienna talks.