* Sets no deadline for any military assault
* Helicopter strikes reported after announcement
* Defence Ministry says air raids kill over 50 militants (Adds defence ministry saying 50 militants killed on Tuesday)
By Ahmed Rasheed
BAGHDAD, Jan 22 (Reuters) - Iraqi Prime Minister Nuri al-Maliki said on Wednesday it was time to clear al Qaeda-linked militants out of the rebel-held city of Falluja, but set no deadline for any military assault.
The Islamic State in Iraq and the Levant (ISIL), an al Qaeda offshoot also on the frontlines of Syria's civil war, overran Falluja with help from other Sunni Muslim groups on Jan. 1.
Iraqi troops and security forces have set up a loose cordon around the city, 50 km (31 miles) west of Baghdad, and have clashed sporadically with insurgents inside, but Maliki has said community leaders and tribesmen should force ISIL to withdraw, in order to spare Falluja more bloodshed and destruction.
"The time has come to settle this issue and end the presence of this gang in this city and save its people from their evil," Maliki said in his weekly televised address to the nation.
Three hours later, helicopter gunships bombarded eastern and northern districts of Falluja, residents said. It was not clear if that was the prelude to wider military action. Helicopters have been in action before on the outskirts of the city.
On Tuesday, Iraqi air force strikes killed more than 50 militants of various Arab nationalities and destroyed large amounts of ammunition in the western province of Anbar, a Defence Ministry statement said. It did not say exactly where the raids on "gatherings of terrorist groups" took place.
Maliki again urged the people of Falluja to "to take crucial positions on the presence of those dirty people without losses and without sacrifices," but set no precise time limit.
"Those criminals are seeking to ignite sectarian strife and to end up with the division of Iraq," Maliki said.
Maliki faces a parliamentary poll on April 30 with violence in Iraq at its worst since Sunni-Shi'ite killings peaked in 2006-2007. His critics say his policies have fuelled grievances among minority Sunnis, driving some into the arms of ISIL, which has also exploited the war in Syria to make a comeback in Iraq.
ISIL militants, who are greatly outnumbered by armed tribesmen in Falluja, have kept a generally low profile, telling mosque congregations repeatedly that their mission is to protect the population, not to impose their harsh version of sharia law.
However, ISIL circulated leaflets last week announcing the formation of a "Committee for the Promotion of Virtue and Prevention of Vice", which recalled memories of the Islamic courts that meted out rough justice in Falluja when it was controlled by a hardline Islamist council in 2005 to 2006.
While people in Falluja are hostile to Maliki's Shi'ite-led government, many fear a full-scale army attack that would echo two fierce U.S. assaults on insurgents there in 2004. Tens of thousands of people have fled the city, U.N. officials say.
Efforts to negotiate a solution have so far failed. Tribal chiefs and clerics met on Sunday to pick a new mayor and police chief, but ISIL rejected the outcome because it had not been represented in the talks, participants in the meeting said.
ISIL militants have brought more fighters and weapons into Falluja in the last three weeks, and other armed groups have proliferated in the security vacuum. Residents said they could not tell the allegiance of the roaming gunmen.
Two days ago, armed men abducted a former Falluja police chief in the city's southern outskirts. Relatives and tribal leaders said they were seeking his release by paying a ransom.
"The situation in Falluja is critical and getting out of control," said one tribal leader. "Everyone is carrying guns and it would only take a spark to ignite a war in the city." (Writing by Alistair Lyon; Editing by Alister Doyle)