Military forces clash with Islamic State near Falluja, bomb city centre

Iraqi forces clashed with Islamic State militants near Falluja on Monday while bombing central districts in the initial hours of an offensive to retake the militant stronghold just west of Baghdad that could last several weeks.

Some of the first direct engagement occurred in al-Hayakil area on the city's southern outskirts, a resident said. Troops also approached the northern suburb of Garma, the top municipal official there said, to clear out militants before turning attention towards the city centre.

Air strikes and mortars overnight targeted neighbourhoods inside the city proper where Islamic State is thought to maintain its headquarters. But the bombardment had eased by daylight.

Iraqi military spokesman Brigadier General Yahya Rasool, speaking on state television, described the forces' advance as "careful" and reliant on engineers to dismantle roadside bombs planted by the militants.

Falluja, a longtime bastion of Sunni Muslim jihadists, 50 km (30 miles) from Baghdad, was the first city to fall to Islamic State, in January 2014. Six months later, the group declared a caliphate spanning large parts of Iraq and neighbouring Syria.

Iraqi forces have surrounded the city since last year but focused most combat operations on IS-held territories further west and north. The authorities have pledged to retake Mosul this year in keeping with a U.S. plan to dislodge Islamic State from their de facto capitals in Iraq and Syria.

But the Falluja operation, which is not considered a military prerequisite for advancing on Mosul, could push back that timeline. Two offensives by U.S. forces against al Qaeda insurgents in Falluja in 2004, which left the city badly damaged, each lasted about a month.

There are currently between 500 and 700 IS militants in Falluja, according to a recent U.S. military estimate.

Army helicopters were shelling IS positions in nearby Garma and targeting movement in and out of the area in order to weaken resistance enough for ground troops to enter, Mayor Ahmed Mukhlif told Reuters.

The defence minister and army chief of staff visited part of that northern axis on Monday, a ministry statement said.

POPULATED CITY

Prime Minister Haider al-Abadi, who also faces political and economic crises in the major OPEC producer, visited a command centre set up nearby to oversee operations, exchanging his suit for the black uniform of an elite commando unit.

Announcing the offensive in a late-night speech, Abadi said it would be conducted by the army, police, counter-terrorism forces, local tribal fighters and a coalition of mostly Shi'ite Muslim militias.

Iraqi officials say the militias, including ones backed by Iran, may be restricted to operating outside the city limits, as they were largely in the battle for nearby Ramadi six months ago, to avoid aggravating sectarian tensions with Sunni residents.

State television showed footage of armoured vehicles sitting among palm groves on the city's outskirts, a green tracer glow emanating from shells and machine gun fire.

Video showed a family standing in the daylight outside a simple one-storey home, cheering and waving a white flag as a military convoy passed by.

The government has called on civilians to flee and said it would open safe corridors to areas south of Falluja. Residents living in the centre said they had moved to relative safety in outlying northern areas but roadside bombs were preventing them from leaving the city.

Iraqi and U.S. officials estimate there are as many as 100,000 civilians still living in Falluja, a city on the Euphrates river whose population was three times that size before the war. A six-month siege has created acute shortages of food and medicine, pushing the city towards humanitarian crisis.