Syria conflict: Central Damascus hit by clashes

Fighting is intensifying across the Syrian capital Damascus, where the military has deployed tanks and helicopters, activists say.

Shooting was reported in one of the main central streets and a square housing the Central Bank.

Rebel forces say they have launched an all-out assault on the capital, calling it Operation Damascus Volcano.

UN envoy Kofi Annan has held talks with Russian President Vladimir Putin in Moscow over the crisis.

Mr Putin told reporters after meeting Mr Annan that Russia still backed the envoy's six-point peace plan, which called for a ceasefire and talks between the government and opposition.

Russia and China have consistently refused to back any measures that hint at intervention in Syria, or ask for Mr Assad to step down.

With international diplomacy virtually paralysed by big-power splits over how to tackle the Syrian crisis, the clashes in Damascus seem to have carried the conflict into a new phase.

The fighting in the capital may have started on Sunday as a case of security forces tackling armed rebels displaced by a crackdown on the suburbs. But the Free Syrian Army has now declared that Operation Damascus Volcano is under way. The Muslim Brotherhood, the biggest and most organised opposition group, has called it a "decisive battle" and urged all Syrians to join a nationwide civil insurrection.

The regime is clearly discomfited. With parts of the capital's centre paralysed, and thousands of residents displaced within the city limits, state media have dropped all mention of the Damascus fighting.

The UN has until Friday to renew the mandate for observers in Syria, and Western nations want the two nations to back tougher measures to stop the fighting.

UN Secretary-General Ban Ki-moon has landed in Beijing, where he called for rapid unified action by the Security Council to tackle the crisis.

In other developments:

Violence is continuing to spread across Syria and in the capital Damascus as rebels - now better-equipped and more organised - confront the army and government-backed militia.

The rebel Free Syrian Army said it had launched Operation Damascus Volcano, and has called for an escalation of attacks on regime targets and the blocking of main roads all around the country.

One of the biggest and most organised opposition groups, the Muslim Brotherhood, has called on all Syrians to join what it called a decisive battle.

Witnesses say the government's military deployment in Damascus is the biggest since protests against President Bashar al-Assad's rule began in March last year.

Clashes were reported in a major thoroughfare, Baghdad Street, the first time fighting has reached central Damascus since the conflict began.

Nawaf al-Fares does not look at first glance like a man who has just defected from a regime he calls "murderous criminals". Neatly dressed in suit and tie, he was until last week Syria's ambassador to Iraq and is the most senior diplomat to defect so far from the rule of President Bashar al-Assad. Sitting now in a luxury hotel in the Gulf state of Qatar, he piles one accusation after another against the regime he served for 34 years.

He accuses his former masters - without offering proof - of colluding with al-Qaeda to carry out mass-casualty bombings on its own citizens to discredit the opposition. He says the regime, if cornered further, "will not hesitate to use chemical weapons".

This is a serious allegation from a defector with some inside knowledge, but Mr Fares is not a scientist nor a soldier. And his words have disturbing echoes of the sort of claims being trumpeted about Saddam's mythical WMD in the run-up to the 2003 invasion of Iraq.

Nawaf Fares does of course have a vested interest in discrediting the regime which he has just deserted.

Also, machine-gun fire was reported in nearby Sabaa Bahrat square, site of the Central Bank and scene of several major pro-government demonstrations.

Activists reported continued clashes on the south-western side of the city, including in Midan.

"The army is shelling al-Midan hysterically; the collapsing regime has gone mad," one activist told AFP.

Fighting is also said to have broken out on the other side, at Barzeh and Qaboun. Attack helicopters were seen there firing rockets for the first time since the uprising began.

State media said security forces were pursuing remnants of a "terrorist gang" in Nahr Eisha.

Syria is known to have a significant stockpile of chemical weapons. There have been growing concerns in neighbouring countries and among Western governments about the security of such weapons should the government fall.

Asked if he thought President Assad might use chemical weapons against the opposition, Mr Fares told BBC security correspondent Frank Gardner that he would not rule it out, describing Mr Assad as "a wounded wolf".

Mr Fares's claim that Sunni Muslim militants in al-Qaeda are collaborating with a government dominated by those from the minority Allawite sect will surprise many.

Challenged on his view that al-Qaeda was collaborating with the government despite this, Mr Fares said: "There is enough evidence in history that lots of enemies meet when their interests meet."

Nawaf Fares talks to the BBC's Frank Gardner

He added: "Al-Qaeda is searching for space to move and means of support, the regime is looking for ways to terrorise the Syrian people."

Mr Fares held senior positions in the ruling Baath Party and powerful security services, and served as governor in several provinces.

"It doesn't occur to any Syrian, not only me, that Bashar al-Assad will let go of power through political interventions... He will be ousted only by force," Mr Fares said.

Mr Fares was dismissive of Mr Annan's visit to Russia, saying success there was "impossible".

"Several months have passed and... the regime hasn't implemented a single article of [Kofi Annan's] plan."