BEIRUT/baghdad - The Islamic State group captured a Jordanian pilot on Wednesday after his warplane from the US-led coalition was reportedly shot down while on a mission against the jihadists over northern Syria.

A senior Jordanian military official confirmed the pilot was seized, saying his plane went down in Syria's Raqa region, a militant stronghold, early on Wednesday. "The pilot was taken hostage by the IS terrorist organisation," official news agency Petra quoted the official as saying.

Jordan did not say why the plane went down, but both the jihadists and a monitoring group said it was shot with an anti-aircraft missile. It was the first coalition warplane lost since air strikes on IS began in Syria in September.

The Syrian Observatory for Human Rights, a Britain-based monitoring group, said its sources confirmed IS had captured the pilot "after shooting his plane down with an anti-aircraft missile near Raqa city."

Coalition warplanes have carried out regular strikes around Raqa, which IS has used as the headquarters for its self-declared "caliphate" after seizing control of large parts of Syria and Iraq. The IS branch in Raqa published photographs on jihadist websites purporting to show its fighters holding the captured pilot.

One showed the pilot, wearing only a white shirt, being carried from a body of water by four men. Another showed him on land, surrounded by about a dozen armed men. A photograph was also released of the pilot's military identification card, showing his name as Maaz al-Kassasbeh, his birth date as May 29, 1988, and his rank of first lieutenant.

The jihadists claimed to have shot down the warplane with a heat-seeking missile. Images distributed by IS supporters appeared to show the remains of an F-16 fighter jet. Experts said the missile used may have been taken from Syrian rebels or among weapons captured from Syrian and Iraqi troops.

Eliot Higgins, who posts detailed analyses of weapons in Syria and other conflicts on his blog, said IS is known to have several kinds of anti-aircraft weapons including Chinese-made and Soviet-era missiles.

The pilot's father Youssef was quoted by Jordanian news website Saraya as saying the family had been informed by the air force of his capture. He said the military promised it was "working to save his life" and that Jordan's ruler, King Abdullah II, was following events.

Jordan is among a number of countries that have joined the US-led alliance carrying out air strikes against IS.

Saudi Arabia, the United Arab Emirates, Jordan and Bahrain are taking part in the air strikes in Syria alongside the United States.

The extremist IS has committed widespread atrocities in areas under its control, including mass executions and public beheadings.

Suicide bomber kills 33 in Iraq

A suicide bomber killed 33 people and wounded 55 others in Madaen, about 25 km (15 miles) south of Baghdad, on Wednesday, Iraqi police and medical officials said.

The bomber blew himself up near a line of pro-government fighters waiting for their salaries, the officials said, adding they expected the toll to rise. The dead were mostly pro-government fighters, but included at least three soldiers.

"The attacker was wearing an Iraqi army uniform, and an explosive vest packed with ball bearings," a police officer said.  There was no immediate claim of responsibility for the attack, but suicide bombings are a tactic almost exclusively employed by extremists in Iraq, including the Islamic State (IS) group.

The Iraqi government has distributed arms and ammunition to tribesmen, and Prime Minister Haider al-Abadi aims to establish a national guard made up of local fighters, though the necessary law has yet to pass parliament.

Iraqi security forces backed by US-led air strikes, Kurdish forces, Shia militias and tribesmen have clawed back some ground from IS. But major areas, especially north and west of Baghdad, remain outside government control.