State television said the talks were held in a positive atmosphere, without giving details.

Al-Assad told Annan that Damascus was ready to "render successful any sincere effort" to solve its crisis, state news agency SANA reported.

"But no political dialogue or process will succeed as long as there are armed terrorist groups working to spread chaos and destabilise the country," SANA quoted al-Assad as saying in talks with Annan in Damascus.

Annan was later due to meet Foreign Minister Walid al-Moallem, the United Nations spokesman in Damascus Khaled al-Masri said.

He is also expected to meet representatives from civil society groups.

Annan's visit, the first since he was named special envoy for the Syrian conflict, came as government forces shelled areas in the northern province of Idlib, according to activists, who said 12 people were killed.

They said government forces were also conducting an operation in the southern province of Daraa to prevent rebels and dissidents from fleeing across the border into Jordan.

In Cairo, Russian Foreign Minister Sergei Lavrov called for an immediate halt to the violence, saying Russia would work with all parties demanding reform in the country.

Lavrov called on armed opposition groups to withdraw from the cities and on the Syrian government to agree to a mechanism to allow humanitarian assistance.

Russia, a key Syria ally, was not trying to protect al-Assad's regime but to "promote a peaceful resolution," he said, warning against outside interference in Syria's domestic affairs.

Last month, Russia and China vetoed a UN draft resolution based on an Arab League plan calling for al-Assad to step down.

In response to Lavrov's remarks, Qatari Foreign Minister Hamad bin Jassim said: "We will not accept a mere halt to the violence. People have been killed. This is not enough."

"There are no armed gangs in Syria, these groups are defending themselves," Jassim said.

Sheikh Hamad, the head of the Arab committee on Syria, demanded that those responsible for killing civilians be held accountable, political prisoners be released, and media and humanitarian assistance be allowed into the country.

He called for the opposition Syrian National Council to be recognised as the legitimate representative of the Syrian people.

"It is time to send Arab and international troops to Syria," Hamad said.

"The time of silence over what is happening in Syria is over. The Arab League decisions must be implemented."

News coming out of Syria cannot be independently verified as the government bars foreign media from the restive areas.

The UN has put the death toll at more than 7500 since the crackdown on protests began.