SYRIAN Prime Minister Wael al Halki has survived a bomb attack on his convoy in Damascus, state media and activists said, as rebels struck in the heart of President Bashar al Assad's capital.

Six people were killed in the blast yesterday, the British-based Syrian Observatory for Human Rights said, the latest in a series of rebel attacks on Government targets including a December bombing that wounded Mr Assad's Interior Minister.

Mr Halki wields little power but the attack highlighted the rebels' growing ability to target symbols of Mr Assad's authority in a civil war that has cost more than 70,000 lives, according to the United Nations.

President Assad picked Mr Halki in August to replace Riyadh Hijab, who defected and escaped to neighbouring Jordan just weeks after a Damascus bombing that killed four of the President's top security advisers.

In comments released by the state news agency SANA but not shown on television, Mr Halki was quoted as condemning the attack as a sign of bankruptcy and failure of the terrorist groups, a reference to rebels battling to overthrow Mr Assad.

The blast shook the Mezze district soon after 9am and sent thick black smoke into the sky. The Observatory said one man accompanying Mr Halki was killed, as well as five passers-by.

State television said: "The terrorist explosion in al Mezze was an attempt to target the convoy of the Prime Minister. Doctor Wael al Halki is well and not hurt at all."

It later broadcast footage of Mr Halki, who appeared composed and unruffled, chairing what it said was an economic committee.

Mezze is part of a shrinking "Square of Security" in central Damascus, where many Government and military institutions are based and where senior Syrian officials live.

Sheltered for nearly two years from the bloodshed and destruction ravaging much of the rest of Syria, it has been sucked into violence as rebel forces based to the east of the capital launch mortar attacks and carry out bombings in the centre.

Mr Assad has lost control of large areas of northern and eastern Syria, faces a growing challenge in the southern province of Deraa, and is battling rebels in many cities.

As part of a counter-offensive, Mr Assad's forces probably used chemical weapons, the United States said last week.

Despite congressional pressure on President Barack Obama to do more to help the rebels, he has made clear he is in no rush to intervene on the basis of evidence he said was preliminary.

Russia, which has criticised Western and Gulf Arab support for the anti-Assad fighters, said attempts by Western countries to expand a UN inquiry into chemical weapons in Syria amounted to a pretext to intervene in the civil war.

"There is not always a basis for the allegations (of the use of chemical weapons)," Russian Foreign Minister Sergei Lavrov said yesterday after meeting the head of the African Union Commission.

He added: "There are probably governments and a number of external players who believe it is fine to use any means to overthrow the Syrian regime. But the theme of the use of weapons of mass destruction is too serious and we shouldn't joke about it. To take advantage of it (to advance) geopolitical goals is not acceptable."