Syrian rebels have launched a coordinated assault on the main prison in the northern city of Aleppo in an attempt to free hundreds of regime opponents believed to be held there.
Aleppo emerged as one of the major fronts in the country's civil war after a rebel offensive there in July, and the fighting since then has settled into a bloody stalemate. The city, Syria's largest, holds strategic and symbolic value, and both sides have taken significant losses in the battle to expand the turf under their control.
The Britain-based Syrian Observatory for Human Rights said rebels detonated two car bombs simultaneously outside the walls of the central prison before trying to storm it. Fierce clashes are taking place between president Bashar Assad's troops and opposition fighters around the area.
The city's central prison is believed to be holding 4,000 prisoners, around 250 of whom are jailed for reasons related to the 26-month-old uprising against Assad's regime.
For weeks, rebel fighters have been battling government troops in the area around the prison to try to seize the facility and free the prisoners. Earlier this month, the rebels overran the headquarters of the government's anti-terrorism forces that is located near the jail.
Meanwhile at least 23 rebel factions, including Islamic groups, joined forces in a push to reopen an arms supply route and retake a key town near Damascus that fell back to regime troops last month. The rebel groups, including the al Qaida-affiliated Jabhat al-Nusra, battled government troops around the town of Otaybah, east of the capital. The army regained control of Otaybah in late April, cutting the opposition's arms route between Jordan and the capital.
There are scores of rebel brigades in Syria. They operate without a unified command structure, but sometimes coordinate to increase their fighting power on individual operations.
More than 70,000 people have been killed since the revolt against Assad's rule erupted in March 2011, and over a million more have sought shelter in neighbouring countries. Millions of others have been displaced inside Syria.
In Jordan, the UN refugee agency warned that the relentless fighting has been driving unprecedented numbers of Syrians into Lebanon, Jordan, Turkey and Iraq, straining the countries' water and food resources to the limit.
:: The UN General Assembly is poised to approve an Arab-backed resolution calling for a political transition in Syria and strongly condemning president Bashar Assad's regime for its escalating use of heavy weapons. The 193-member world body is due to vote on the resolution which also condemns Syria's "gross violations" of human rights.