BAGHDAD - A suicide bomber killed at least 27 militiamen on the outskirts of the Iraqi town of Jurf al-Sakhar on Monday after security forces pushed Islamic State militants out of the area over the weekend, army and police sources said.

Holding Jurf al-Sakhar is critical for Iraqi security forces who finally managed to drive out the Sunni insurgents after months of fighting. It could allow Iraqi forces to prevent the insurgents from edging closer to the capital Baghdad, sever connections to their strongholds in western Anbar province, and stop them infiltrating the south.

The group has threatened to march on Baghdad, home to special forces and thousands of militias expected to put up fierce resistance if the capital comes under threat. Gains against Islamic State, an al Qaeda offshoot made up of Arab and foreign fighters, are often fragile even with the support of US airstrikes on militant targets in Iraq and neighbouring Syria.

As Iraqi government soldiers and militias savoured their victory and were taking photographs of Islamic State corpses on Sunday, mortar rounds fired by Islamic State fighters who had fled to orchards to the west rained down on Jurf al-Sakhar.

The blast hit the militiamen, killing dozens and scattering body parts, according to a Reuters witness. The next significant fighting near Baghdad is expected to take place just to the west in the Sunni heartland Anbar province.

Meanwhile, the US-led coalition carried out fresh air strikes Monday against militants in Syria and Iraq as Washington called for the battle against the Islamic State group to be taken to the Internet. The US military said its fighter jets and bombers carried out four more air strikes near Kobane on Sunday and Monday, destroying five IS vehicles and an IS-held building.

But there was no sign yet of promised reinforcements for the town’s defenders, despite plans announced last week for Iraqi Kurdish peshmerga forces armed with heavy weapons to join the battle.

A senior Iraqi Kurdish official said the deployment was being held up by Turkey, which has agreed to allow the peshmerga to pass through its territory. “We are ready to send them,” Mustafuz Qader, who heads the ministry responsible for the peshmerga, told journalists. “We are awaiting the stance of the state of Turkey and because of this have not sent any forces,” he said, without elaborating. Kobane has become a crucial symbol in the battle against IS, an extremist Sunni group that has seized large parts of Syria and Iraq, declared an Islamic “caliphate” and committed widespread atrocities.

Washington has forged an alliance of Western and Arab nations to combat the group and on Monday met with coalition partners in Kuwait City to boost efforts to counter the militants’ online propaganda.

Retired US general John Allen, who is coordinating the US-led campaign against IS, told participants that the group was promoting its “horrendous brand of warfare” online, where it “recruits and perverts the innocent”.

“It is only when we contest ISIL’s presence online, deny the legitimacy of the message it sends to vulnerable young people... it is only then that ISIL will truly be defeated,” Allen said, using an alternative name for the group.

After the talks the coalition partners promised to take steps to boost efforts to prevent the recruitment of foreign fighters for IS, including online. IS operates a sophisticated presence online, posting frequent propaganda videos and publishing its own expertly designed magazine. Concern is growing over the group’s online influence in attracting foreign fighters and promoting attacks by disaffected Muslims on Western targets.

Meanwhile, a teacher from northern England who bought equipment for use by Islamic State (IS) militants in Syria was convicted on Monday of terrorism offences, police said. Jamshed Javeed, a 30-year-old science teacher at a secondary high school in Bolton, pleaded guilty at a court in London to assisting others to commit acts of terrorism and preparing to travel to Syria himself, the police said in a statement.

Security officials say some 500 Britons, most with Muslim immigrant backgrounds, are believed to be fighting in Iraq and Syria, though the true number could be much higher. They say any returning fighters would pose a threat to national security.

The US military said the coalition had also carried out seven new strikes against IS in Iraq on Sunday and Monday, including near the key Mosul dam and southeast of the militant bastion of Fallujah.

Iraq has struggled to regain territory taken by IS in a lightning offensive in June, though it announced at the weekend that its forces had retaken the strategic town of Jurf al-Sakhr south of Baghdad.

Sources said Monday that a suicide bomber had subsequently detonated an explosives-rigged Humvee armoured vehicle near security forces and allied militiamen in the area, killing at least 14.

Syrian rebel fighters were meanwhile reported to have launched a major assault on the government-held city of Idlib in a bid to consolidate their control over the country’s northwest.

Rebels seized control of most of Idlib province early in Syria’s three-and-a-half-year-old civil war but troops have held out in the provincial capital, resupplied by air.

Fighters of Al-Qaeda affiliate Al-Nusra Front and Islamist rebel units attacked the city from all sides, the Syrian Observatory for Human Rights said.

“Since dawn, fierce fighting has raged at army checkpoints all around Idlib city,” said the Britain-based monitoring group, which has a wide network of sources inside Syria.

Rebels made a previous attempt to take the city earlier this year but Monday’s assault was “the biggest since the beginning of the revolt” in 2011, Observatory director Rami Abdel Rahman told AFP.

The rise of IS has destabilised large parts of the region, including in Syria’s neighbour Lebanon where clashes at the weekend saw thousands flee their homes in the country’s second city Tripoli.

Lebanese soldiers deployed in Tripoli’s impoverished Sunni district of Bab al-Tebbaneh on Monday without incident, facing no resistance after clashes that killed 11 soldiers and five civilians between Friday and Sunday.