Syrian army shelling of a mosque in the central city of Homs killed a prominent cleric Friday, while rebels in Aleppo to the north made a fresh advance, a monitoring group said.

"Two people were killed in shelling by regime troops of the Raees mosque in the Waar neighborhood" of Homs city, said the Syrian Observatory for Human Rights.

The group's director Rami Abdel Rahman said one of those killed was Sufwan Mashraqa, a Sunni Muslim cleric who was leading Friday prayers in the mosque.

Mashraqa was a former head of the city's department for religious affairs.

Amateur video distributed by activists showed the cleric giving a sermon. When the sound of shelling begins, scores of worshipers are overtaken by panic.

Waar is a majority Sunni district of Homs and is located near a small section of the city still under rebel control.

It has become home to tens of thousands of people who have fled other parts of the city. Waar sees daily fighting and shelling.

Elsewhere in Syria, rebels battling to topple President Bashar Assad made a fresh advance in Aleppo, taking control of Kindi hospital in the north of the city, said the Observatory.

"We have confirmed reports that the Islamists and the (al-Qaida-affiliated) Al-Nusra Front have taken near-total control of the Kindi hospital, and that they killed at least 20 regular troops there," said Abdel Rahman.

The fighters have also taken some 30 regulars prisoner, he added.

The takeover came after "two Al-Nusra Front fighters detonated themselves at checkpoints guarding the facility", he told Agence France Presse.

Once a hospital, the facility was turned into a base for Assad loyalist troops several months ago.

Speaking to AFP via the Internet, Abu Omar said "it gives fighters in the north of the city easier access to the nearby countryside."

Shahba Press, a network of citizen journalists in Aleppo, said the takeover "comes a year into a (rebel) siege" of the hospital.

The advance comes days into what activists have described as an "unprecedented" bombing campaign on Aleppo's city and province.

On Friday, air raids struck several villages in the countryside. Dozens were killed in raids over Aleppo in the past week.

In southern Syria's Jassem, meanwhile, the number of people killed from a Thursday aerial attack using TNT-packed crude barrels has risen to 17, including four children, said the Observatory.

Near Damascus, fresh fighting broke out in Maalula, an ancient Christian town located in the Qalamoun mountains.

The fighting pitted rebels and al-Qaida-linked jihadists against troops backed by paramilitary fighters.

More than 126,000 people have been killed in Syria's war since March 2011, and millions more forced to flee their homes.