Syrian rebels have battled government troops near a landmark 12th century mosque in the northern city of Aleppo, while fierce clashes raged around a police academy west of the city, activists said.

The fighting near the Umayyad Mosque in the walled Old City on Tuesday threatened to further damage the historic structure, part of which was burned during clashes last year.

The Britain-based Syrian Observatory for Human Rights reported intense clashes with heavy gunfire and explosions near the mosque. Syria's state news agency said "terrorists" had detonated explosives near the building's south wall, causing "material damages."

The mosque, also known as the Great Mosque of Aleppo, sits near a medieval covered market in the Old City, which is a UNESCO World Heritage site. The mosque was heavily damaged in October, 2012, just weeks after a fire gutted the market.

Homemade rockets

To the west of Aleppo, activists reported fresh fighting on Tuesday near the police academy that has become a key government military installation.

The Observatory said the two sides were shelling each other's positions while the government launched airstrikes in the area.

Videos posted online in recent days shows rebel groups firing homemade rockets and mortars at the academy and blasting it with captured tanks.

The Observatory said the dead in the last two days of fighting in the area included 26 rebel fighters, 40 soldiers and five pro-government fighters.

The police academy, which activists say the government has turned into a military base, has recently emerged as a new front in the battle for Aleppo.

Losing the facility would hinder the regime's ability to shell opposition areas and support its troops inside the city.

The fighting has largely destroyed Aleppo and caused humanitarian conditions for the city's remaining civilians to plummet.

On Tuesday, Human Rights Watch said more than 141 people, including 71 children, had been killed in at least four missile strikes by the Syrian government in and near the city of Aleppo last week.

The New York-based group said the strikes hit residential areas and called them an "escalation of unlawful attacks against Syria's civilian population."

A Human Rights Watch researcher who visited the sites said up to 20 buildings were destroyed in each area hit by a missile. There were no signs of any military targets in the residential districts, located in rebel-held parts of Aleppo and its northern countryside, said Ole Solvang, the researcher.

"The extent of the damage from a single strike, the lack of (military) aircraft in the area at the time, and reports of ballistic missiles being launched from a military base near Damascus overwhelmingly suggest that government forces struck these areas with ballistic missiles," HRW said in its report.

End supply of arms

UNICEF said in a statement that it is "appalled" by the deaths of children, and called on all parties in the conflict to "ensure that civilians, and children especially, are protected, at all times."

UN political chief Jeffrey Feltman condemned the bombings in Aleppo and Damascus and repeated a call "to immediately end the supply of arms to both sides in this brutal conflict."

He pledged that "perpetrators of serious crimes will be held accountable."

The missile attacks have outraged the leaders of Syria's exiled opposition who have accused their Western backers of indifference to the suffering of civilians caught up in the conflict.

PHOTO CAPTION

A citizen journalism image provided by Aleppo Media Center AMC which has been authenticated based on its contents and other AP reporting, shows people searching the rubble for dead bodies and injured victims at a site were houses were hit by a missile attack by Syrian government forces, in the neighborhood of Ard Al-Hamra, Aleppo, Syria, Tuesday, Feb. 26, 2013.

Aljazeera