Russia on Monday rejected Arab and Western calls for a deadline to be set for the Syrian regime's implementation of a peace plan put forward by international mediator Kofi Annan.

"Ultimatums and artificial deadlines rarely help matters," Foreign Minister Sergei Lavrov said while on a visit to the former Soviet nation of Armenia.

Lavrov added that only the UN Security Council on which Russia wields veto power could put any time restrictions on Syrian President Bashar al-Assad's compliance with the six-point initiative.