Iraqi government forces battling al-Qaeda-linked militants intensified airstrikes and artillery fire on the rebel-held city of Fallujah on Sunday, and at least seven people were killed there, according to hospital officials and tribal leaders.

Religious and tribal leaders in the city, 30 miles west of Baghdad, said they feared an imminent assault by the army to expel militants and end a three-week standoff that has driven thousands of people from their homes. The al-Qaeda-linked Islamic State of Iraq and the Levant, which is also fighting in neighboring Syria, took control of Fallujah and parts of nearby Ramadi, the provincial capital, on Jan. 1 with the help of sympathetic armed tribesmen.

The rebels and government forces have since been in pitched battles for control of the two key cities in Anbar province.

Iraqi security forces have set up a loose cordon around Fallujah, the scene of two major battles with U.S. troops in 2004, and have clashed sporadically with insurgents inside. But they have held off from an all-out offensive, seeking to give community leaders and tribesmen time to convince the gunmen to withdraw. “There is no time left for talks, and we’re afraid a military solution is looming,” said a local cleric. “A third Fallujah battle is at the doors.”

Iraqi security officials said no deadline had yet been set for a military operation in Fallujah, but voiced concern that further delay may allow insurgents to strengthen their positions.

“We have not received green light to start an assault, but the longer we wait means al-Qaeda could get more powerful and complicate our job to defeat them,” a special forces officer said.

Meanwhile in Ramadi, where tribesmen have helped the army counter the al-Qaeda insurgents, official sources said militant groups had retaken the eastern areas of the city after security forces withdrew. The Defense Ministry said that 20 ISIL militants had been killed in the military operation in eastern Ramadi.

The conflicts in Anbar province are just a component of the violence that has broken out in Iraq in recent months as Sunni militants take on the Shiite-backed government. Car bombings and shootings killed 13 people across Iraq on Sunday, authorities said.

Vice President Biden telephoned Iraqi Prime Minister Nouri al-Maliki on Sunday to express that the United States continues to support Iraq in its fight against the al-Qaeda-linked militants.

Biden commended al-Maliki’s government for its efforts to integrate tribal forces fighting ­al-Qaeda into Iraqi security forces, and to provide compensation for those injured and killed fighting the militants.

— Reuters