BEIRUT: A powerful car bomb exploded Friday outside a mosque in a pro-government district of central Syria, killing 14 people in the latest violence to hit the war-shattered city, state-run Syrian television reported.

The bombing occurred as worshippers left the Bilal al-Habshi mosque on the edge of Akrama after attending Friday prayers, the report said, and also wounded at least 50 people.

The area, populated mainly by Alawites, members of President Bashar Assad's minority sect, repeatedly has been targeted by car bombs in recent months.

Opposition activists also reported the blast. The Syrian Observatory for Human rights said the explosion killed at least nine people, adding that the number likely would rise because many of the wounded were in critical condition.

The attack coincides with a crushing offensive by government forces aimed at retaking the last rebel bastions in the historic quarters of the old city of Homs. The last few days has seen some of the fiercest fighting there in months, and the government claimed more progress on Friday.

A military official quoted by the state-run news agency said troops seized several buildings in the Wadi al-Sayeh area, including the landmark St. George church.

The old neighborhoods of Homs, a city often referred to as the capital of the revolution, is the last major stronghold for rebels in central Syria, and the fight to take it underscores how emboldened Syrian forces have become in opposition-held areas, bolstered by fighters from the Lebanese Shiite militant group Hezbollah.

Activists say more than 150,000 people have been killed in the Syrian conflict since it began in March 2011 with largely peaceful protests calling for Assad's ouster. The larger fight to topple Assad has been undermined by fierce rebel infighting, particularly since the beginning of the year.

In an audio message posted on militant websites late Thursday, the spokesman of a powerful al-Qaida breakaway group, the Islamic State of Iraq and the Levant, slammed the terror network's chief, blaming him for the widening rift between rival Islamic rebels.

Abu Mohammed al-Adnani accused al-Qaida's top leader, Ayman al-Zawahri, of "deviating from the right approach" and betraying the cause of jihad, or holy war.

Since January, the Islamic State has been engaged in fierce fighting against an al-Qaida affiliate called the Nusra Front. Thousands of fighters have been killed.

The fighting intensified after al-Zawahri stepped into the rivalry. The Islamic State rejected his orders that the Nusra Front take the lead among Islamic fighters in Syria.

"The al-Qaida of today is no longer the al-Qaida of jihad, but its command has become a pickaxe to demolish the Islamic State," al-Adnani said.

He said that al-Qaida's leadership has been calling ISIL followers renegades without a proof, inciting other Muslims to kill their fighters.

The shadowy al-Adnani is one of the world's most feared terrorists, infamous for his relentless bombing campaigns against Iraqi civilians, audacious jailbreaks of fellow militants and for expanding the organization into Syria.

His audio message suggested that rebels in Syria will remain locked in the infighting that has eroded their ranks and cost them territory to government forces supporting Assad.

Al-Golani, the Nusra Front leader, called on the Islamic State in February for arbitration by Islamic clerics, but the group did not respond to the initiative.

The infighting escalated few days later after the killing of Abu Khaled al-Suri, who had acted as al-Zawahri's representative in Syria.

Rebels and activists believe he was assassinated by two suicide attackers from the Islamic State.