Activists say Assad forces have clashed with army defectors in Kfar Souseh, where foreign ministry and security agencies are located
A restive district of the Syrian capital that has been a hotbed of dissent against President Bashar al-Assad was rocked by fighting overnight between government forces and army defectors, opposition groups said.
The Local Co-ordination Committees and the Syrian Observatory for Human Rights said the clashes took place in Kfar Souseh early on Sunday morning but there were no immediate reports of casualties. The Damascus district is a high security area, housing the foreign ministry and several security and intelligence agencies. It has also been the scene of frequent anti-Assad demonstrations since the uprising began.
"Violent clashes broke out between rebel fighters and regime troops at a checkpoint in Kfar Souseh district," the Observatory said in a statement. Both the Observatory and LCC said explosions and gunfire were also heard in several other neighbourhoods of Damascus.
The revolt against Assad's regime started in March 2011 with mostly peaceful protests calling for political change. The deadly government crackdown led many opposition supporters to take up arms. Now, the regime is facing an armed insurgency targeting government installations, soldiers and security forces.
In March, the UN said that 9,000 people had been killed. Hundreds more have died since.
Also on Sunday, Syrian rebels claimed in an internet statement that they carried out a sophisticated attack that killed top political and security officials meeting in the capital. The posting claimed those killed included Major General Assef Shawkat, the deputy chief of staff for security affairs; defence minister Dawoud Rajha; interior minister Mohammad al-Shaar and former defence minister, Hassan Turkmani.
Al-Shaar denied the reports in a phone call to state-run Syrian TV, saying they were "laughable".
"I am speaking to you from my office at the interior ministry," he said.
Turkmani also called the station and said the reports were proof of "media bankruptcy".
"My colleagues and I are well and carrying out our duty to serve the country ... these are blatant lies," he said. The station later interviewed Turkmani in his office, denying the claims.
Syrian officials rarely respond to claims and statements issued by the opposition and their quick denials on Sunday were unusual.
Clashes in the heart of the Syrian capital have become more common recently but are still rare compared with other opposition strongholds in Syria that witness deadly violence almost daily.
The Local Co-ordination Committees said "huge reinforcements" were brought in to Kfar Souseh in the wake of the overnight fighting.
A ceasefire that started last month has never really taken hold, undermining the rest of international envoy Kofi Annan's plan, which is supposed to lead to talks to end the 15-month crisis.
World powers remain divided on how to end Syria's crisis. The US and other western and Arab nations have called for Assad to leave power, and the US and European Union have placed increasingly stiff sanctions on Damascus. But with Russia and China blocking significant new UN penalties, US officials are trying to get consensus among other allies about ways to promote Assad's removal.
Visiting Annan deputy Jean-Marie Guehenno held talks on Sunday with a three-man delegation from an opposition group inside Syria.
Abdul-Aziz al-Kheir, a spokesman for the National Co-ordination Body for Democratic Change in Syria, said the talks centred on implementing Annan's plan. He said his group demanded "a genuine and overall ceasefire" as the only path to a political process that could solve the crisis.
President Barack Obama said on Saturday that the members of the G8 industrial nations supported the UN's peace plan for Syria, but added that it has not taken hold fast enough.

