Iraq battle for Ramadi
Members of the Iraqi army and Shi'ite fighters launch a mortar towards Islamic State militants on the outskirts of the city of FallujaReuters

Iraq has called for more volunteers to retake control of the strategically important city of Ramadi, capital of Anbar, after Baghdad deployed tanks and artillery around the city.

With thousands of residents having fled and scores of militants arriving, Ramadi is likely to witness a deadly battle in the coming days as Iraqi forces close in.

Local government officials in the province have urged the inhabitants to join the "Battle of Anbar" against the Islamic State (Isis).

The Baghdad administration has also admitted to the shortage of forces in the west of the province to combat the IS Sunni insurgents. Thousands of Shiite militiamen have already been drafted in to fight the Islamists.

"IS penetrated the city, but Habbaniya [Shiite forces] and eastern Husaybah residents and the Al-Bufahd tribe resisted ISIS and retook their own territory. We ask the Iraqi government to supply us weaponry, because we have controlled the situation and deployed our forces all around," a local was quoted as saying by the Kurdish news agency Rudaw.

Local reports suggest the IS insurgents are drawing up defensive strategies to fortify their hold on Ramadi including by planting landmines. The IS group, which pledged to implement harsh Islamic Shariah law once it is in full control of Ramadi, is also releasing dozens of prisoners in the city.

"Islamic State used loudspeakers urging people who have relatives in prison to gather at the main mosque in the city centre to pick them up. I saw men rushing to the mosque to receive their prisoners," a 37-year-old school teacher from Ramadi, Saed Hammad al-Dulaimi, told Reuters.

The US has also agreed to intensify its aerial campaign against the jihadists, who staged a surprise attack on Ramadi last week, capturing government buildings and mosques.

"The United States will be very supportive of multi-sectarian efforts who are taking command-and-control orders from the Iraqi central government," White House spokesperson Josh Earnest told reporters.

Washington is also mulling over further measures in stepping up training for the local tribe in boosting their fight against the IS.