Shelling by the Iraqi army in the city of Fallujah has killed more civilians, hospital sources and witnesses have said, amid allegations that government forces were using barrel bombs in an attempt to drive out anti-government fighters from the area,

The use of barrel bombs in civilian areas is banned under international conventions given their indiscriminate nature.

But Mohammed al-Jumaili, a local journalist, told Al Jazeera that the army has dropped many barrel bombs "targeting mosques, houses and markets" in Fallujah.

Local hospital sources said the situation was getting worse for many people who had been trapped in the city since the army cut off a key bridge.

The Iraqi government has denied the use of barrel bombs and asserted that it was fighting in a "humane way".

Al Jazeera's Imran Khan, reporting from the capital Baghdad, said that despite the government's denial, there was strong evidence that barrel bombs havd been used in Fallujah.

"We have spoken to people, including witnesses and experts, in Fallujah who say the government has been using barrel bombs," he said.

"Pictures have also been given to Al Jazeera showing barrel bombs used in Iraq. Barrel bombs are very distinctive looking, they are oil barrels that are stuffed with explosives and thrown from helicopters."

Deadly kidnapping

Meanwhile, unidentified gunmen have killed dozens of government soldiers in Fallujah and Mosul.

Police sources told Al Jazeera that 22 soldiers who had been kidnapped in Fallujah on Friday were killed on Saturday night.

In a separate incident, fighters kidnapped a group of soldiers from a small base in Ain al-Jahash, south of Mosul, on Saturday, and later shot them dead, police sources said on Sunday.

A medical official, who confirmed the casualty number in the Ain al-Jahash attack, said 11 troops had their hands tied behind their backs and suffered close-range gunshots to the head, the AP news agency reported.

Fighters opposed to the Iraqi government frequently target members of the security forces, but it is rare such large number of soldiers to be kidnapped at once, especially from a military facility.

The killings come as the country suffers a protracted surge in bloodshed, the worst the country has experienced since the brutal sectarian fighting that peaked in 2006-2007 and killed tens of thousands of people.

The government has blamed the upsurge in violence on external factors, such as the civil war in Syria, but analysts say there is also widespread resentment among the Sunni Arab community over alleged mistreatment by the Shia-led government.