AMMAN (Reuters) - Heavy fighting erupted in Damascus on Wednesday after opposition fighters launched a coordinated offensive from the suburbs against President Bashar al-Assad's forces, breaking a lull in the capital, opposition campaigners said.

The authorities closed the main Abbasid Square and the Fares al-Khoury thoroughfare as fighters attacked road blocks and fortifications with rocket-propelled grenades and mortar rounds, said several activists speaking form the capital.

"The areas of Jobar, Zamalka, al-Zablatani and parts of Qaboun and the ring road have become a battleground," activist Fida Mohammad said from the district of Qaboun.

Another activist said an army tank stationed at the main al-Kabbas roadblock on the ring road had been destroyed. Residents reported the sound of explosions across eastern and northern district of the capital.

(Reporting by Khaled Yacoub Oweis, Amman newsroom)