DAMASCUS- Russia called on Saturday for a political transition in Syria, as Switzerland prepared to petition the International Criminal Court to open a case on war crimes in the country.

Violence raged unabated with regime warplanes carrying air strike near the capital, a car bomb explosion in Damascus province and the murder of an athletics champion shot dead by gunmen, said the Syrian Observatory for Human Rights.

A day after UN-Arab League special envoy Lakhdar Brahimi met Russian Deputy Foreign Minister Mikhail Bogdanov and US Deputy Secretary of State William Burns, Moscow reiterated its long-held position that only Syrians can decide their own fate.

"In our opinion, the priority task is to immediately stop any violence and bloodshed as well as provide Syrians including internally displaced persons and refugees with humanitarian aid," a foreign ministry statement said.

But it also added: "At the same time it is necessary to secure the launch of a political transition process in Syria aimed at enshrining in law guaranteed and equal rights of all ethnic-confessional groups of this country."

Moscow, a key Damascus ally, also reiterated its support for a transition plan that was agreed in Geneva on June 30, 2012, but has since split world powers.

In a separate statement, the ministry said Bogdanov also met a Syrian delegation led by Michel Kilo, a prominent anti-regime activist who opposes foreign intervention. Bogdanov pledged to continue "active contacts" with both Damascus and the opposition, it added.

Inside Syria, regime warplanes bombarded the outskirts of Mleha just southeast of Damascus "a day after rebels assaulted an air force security building there." the Britain-based Observatory said.

The Observatory, which relies on a network of activists and medics on the ground, also reported a car bomb explosion that ripped through the Abu Arif area of Sbeineh in Damascus province.

There were no immediate reports of casualties, but the Observatory said the explosion caused widespread damage.

Also near Damascus, unidentified gunmen "murdered athletics champion Hisham al-Raksha, while he was in his car," said the Observatory.

He won a silver medal in the West Asian cup, and was the official coach of Syria's race-walking national team.

At least 47 were killed in violence nationwide on Saturday, the Observatory said.

Amid unrelenting violence, Switzerland said it will on Monday file a petition signed by 52 countries calling for the ICC to open a case on war crimes in Syria, its foreign minister said.

"Serious war crimes are being committed in Syria. We must make sure they not go unpunished," Swiss Foreign Minister Didier Burkhalter told Swiss national television TSR.

"We're submitting a proposal, now it is up to the Security Council to decide," he added, saying the UN organ could either block or pursue the request.

Since Syria is not a party to the ICC, the world's only permanent war crimes tribunal, a UN Security Council referral is needed for the court to look into crimes committed in the now 22-month conflict.

The United Nations estimates more than 60,000 people have died since the March 2011 outbreak of the revolt, with over 600,000 Syrians registered as refugees in the region.

Escalating violence has in turn led to thousands of low and mid-level defections, when peaceful protests turned violent amid a deadly crackdown on dissent.

In a video posted on the Internet on Friday, a man identifying himself as Jumaa Farraj Jassem, a senior foreign intelligence official, announced his defection. AFP was unable to verify the authenticity of the video.