Jordan vowed Thursday to make every effort to save a pilot captured by the Islamic State group in Syria as Washington denied claims the jihadists had shot down his warplane.
Maaz al-Kassasbeh, a 26-year-old first lieutenant in the Jordanian air force, was captured by IS on Wednesday after his F-16 jet crashed while on a mission against the jihadists over northern Syria.
It was the first warplane lost and the first capture of a serviceman since the coalition launched strikes against IS in Syria in September.
It was also a major propaganda victory for the Sunni extremist group, which released photographs parading the captured pilot.
"The Jordanian government... is making all efforts with several crisis cells to free (the pilot)," government daily Al-Rai said.
"We are confident that our brave one will be released... He has not been forgotten."
The pilot's father, Safi al-Kassasbeh, urged IS to show "mercy" and treat his son a "guest".
"We consider Maaz a guest in the keep of brothers," Kassasbeh told AFP, adding that he was praying for his release.
Jordan, along with Saudi Arabia, the United Arab Emirates and Bahrain, has joined the US-led coalition carrying out air strikes against IS after it seized control of large parts of Syria and Iraq.
Kassasbeh's plane went down near the city of Raqa, which IS has used as its de facto capital and where coalition warplanes have carried out regular strikes.
The jihadists and the Syrian Observatory for Human Rights said the plane was downed by an anti-aircraft missile, raising concerns for other coalition aircraft.
But the US military said "evidence clearly suggests that ISIL did not down the aircraft", using another name for IS, without giving a cause for the "crash".
"We strongly condemn the actions of ISIL, which has taken captive the downed pilot," said Central Command chief General Lloyd Austin.
"We will support efforts to ensure his safe recovery, and will not tolerate ISIL's attempts to misrepresent or exploit this unfortunate aircraft crash for their own purposes."
Jordan's parliament said it would hold IS "responsible for safeguarding the life" of Kassasbeh, describing him as a "hero".
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IS posted pictures online showing its fighters holding the pilot.
One showed a man being carried from a body of water by gunmen. Another showed the same man on land, surrounded by almost a dozen militants.
Messages of support for the pilot flooded Facebook and Twitter under the hashtag "We are all Maaz al-Kassasbeh".
Analyst Mohamed Abu Rummaneh, from the University of Jordan, said he did not expect Amman to reconsider its role in the anti-IS coalition.
"A large majority of Jordanians -- nearly 90 percent according to polls -- consider Daesh (another name for IS) to be an enemy," he said.
But political commentator Labib al-Kamhawi said the government would come under pressure to pull out of the coalition "if, God forbid, anything adverse happened to the pilot".
An activist in Raqa said IS militants were divided over the pilot's fate, with more extremist foreign fighters wanting him executed and others wanting him kept alive.
Jordanian Salafist leader Mohammed Shalabi denounced Amman's participation in the coalition, and warned the war on IS would lead to "deaths and injuries".
UN Secretary General Ban Ki-moon has appealed for the pilot's captors to treat him "in accordance with international humanitarian laws".
- Strikes continue -
Despite the loss of the plane, the coalition carried out more strikes against IS targets, said the Observatory, which relies on a network of sources for its reports on Syria.
On Wednesday, the coalition launched eight strikes against IS positions in Kobane, a town on the border with Turkey which is known as Ain al-Arab in Arabic.
Other strikes hit Bukamal near the Iraqi frontier.
The Observatory said at least 44 IS fighters were killed in clashes with Kurdish militia in the northeastern province of Hasakeh and in Kobane.
Syria's conflict began in 2011 as a peaceful revolt against President Bashar al-Assad but evolved into a multi-front civil war that saw IS grab large swathes of land.