Chinese Foreign Minister urged the world to act with greater urgency to support the mediation efforts of the UN-Arab League's Syria peace envoy Lakhdar Brahimi, state media reported on Wednesday.

Yang Jiechi also repeated a call for all sides in the Syria conflict to cease fire immediately and take steps towards forming a transitional government, the official Xinhua news agency reported.

"The international community should fully cooperate with and support envoy Brahimi's mediation efforts with a more intense sense of urgency and responsibility," the report cited Yang as telling Brahimi during a meeting in Beijing.

"Relevant parties should as soon as possible appoint authoritative representatives to come up with a roadmap for a political transition with the help of envoy Brahimi and the international community," Yang added.

"China believes that the situation in Syria is worsening by the day," he said. "The only realistic way out is to resolve the Syria issue through political channels."

Syrian warplanes bombed rebel targets with renewed intensity on Tuesday after the end of a widely ignored four-day truce between President Bashar al-Assad's forces and insurgents which had been proposed by Brahimi.

China and Russia have vetoed three UN resolutions condemning Assad's government for the violence.

But China has been keen to show it is not taking sides and has urged the Syrian government to talk to the opposition and take steps to meet demands for political change. It has said a transitional government should be formed.

Also on Wednesday, a bomb killed at least six people near a Shi'ite shrine in a suburb of the Syrian capital Damascus, state media and opposition activists said.

State media said 13 people were also wounded in the explosion in the Sayeda Zainab district. The semi-official Addounia television said the bomb was placed in a garbage bag. Another bomb in the area was defused, the station said.

"The explosion occurred just east of the shrine. Lots of people are also wounded," said one of the activists in the area, who declined to be named.

"Security personnel have swarmed the area. It is not clear whether the target was the shrine or a security compound adjacent to it," he added. Groups opposed to President Bashar al-Assad say seven people died in the blast.

The poor neighborhood, inhabited by a mix of Sunni and Shi'ite Muslims, is marked by the colored tile and mirror shrine, located near several security compounds, as well as an office for Shi'ite Iraqi cleric Muqtada al-Sadr.