MOSCOW, Aug. 3 (Xinhua) -- Russia on Friday expressed "deep regret" at Kofi Annan's resignation as joint U.N.-Arab League special envoy to Syria and urged that a successor be found quickly.

The United Nations announced Thursday Annan had advised he would not continue in the role once his mandate expired at the end of August.

The Russian Foreign Ministry said in a statement Russia had supported Annan's work from the start and had jointly worked with all Syrian parties to implement the Geneva declaration, which envisages a Syrian-led transition.

Meanwhile, the ministry also said it regretted the Syrian opposition had refused all proposals to start a political dialogue and that the Western countries had not tried to push the opposition in this direction.

"Moreover, in contradiction with the U.N. Security Council decisions and Geneva (agreements), they (the West) continued all that time to provide political, moral, material-technical and financial support to the Syrian opposition groups, thus encouraging the irreconcilable position of the anti-government forces," the ministry said.

Russia called on the UN to keep its presence in Syria following Annan's resignation, stressing the international efforts to settle the 17-month long Syrian crisis must not be slowed down.

"The Annan peace plan and the Geneva agreements remain important as a guideline for the peaceful settlement of the Syrian problems," the ministry said. It urged all parties to cooperate in seeking a quick end to the violence and launch of the political process.

Annan, who assumed his current post about five months ago, said in Geneva on Thursday he was disappointed at the lack of progress in the Syrian peace process.

Annan's widely accepted six-point plan calls for the withdrawal of heavy weapons and troops from populated areas, a daily halt of fighting for the delivery of humanitarian aid and treatment of the injured, and talks between the government and opposition. Enditem