Jordan said its warplanes launched dozens of new strikes Thursday against the Islamic State group, after vowing a harsh response to the burning alive of a pilot captured in Syria.

The news came as scores of people were killed when rebels unleashed rocket fire on Damascus and President Bashar al-Assad's forces retaliated.

Jordan's military said "dozens of jet fighters" struck IS targets on Thursday morning, "hitting training camps of the terrorist groups as well as weapons and ammunition warehouses".

It did not say where the targets were located -- IS holds swathes of Syria and Iraq -- but said they were destroyed and the aircraft returned home safely.

American F-16 and F-22 jets provided security to the Jordanian fighter planes, with additional support from refueling tankers and surveillance aircraft, US officials said.

Washington has also deployed aircraft and troops to northern Iraq to boost capabilities to rescue downed pilots fighting with the international coalition that is battling IS, a US defence official told AFP.

IS have released a highly choreographed video of the horrifying murder of pilot Maaz al-Kassasbeh, whose death has sparked grief and deep anger in Jordan.

Jordan's military has pledged to "destroy this terrorist group and kill the evil in its own place", saying it would punish IS for the "heinous act" of burning him alive.

King Abdullah II visited the airman's family, who have urged the government to "destroy" the jihadists, to pay his condolences.

Jordan has conducted regular raids against IS across the border in Syria as part of a US-led campaign against the Sunni extremist group.

More than 200,000 people have died since anti-government protests erupted in Syria in early 2011, escalating into a multi-sided civil war that brought jihadists streaming into the country.

At least 66 people, including 12 children, were killed by regime air strikes and shelling on rebel areas around Damascus Thursday, according to the Syrian Observatory for Human Rights.

The assault on the Eastern Ghouta region came after rebels fired more than 100 rockets at the city, killing 10 people including a child, the Britain-based group said.

- Protests after death video -

The gruesome murder of Maaz al-Kassasbeh, captured by IS in December after his F-16 crashed in Syria, has increased support in Jordan for stepped-up military action against the jihadists.

"Jordan will wage all-out war to protect our principles and values," government newspaper Al-Rai wrote in an editorial.

The execution has sparked outrage in Jordan and protests in Amman and Karak, bastion of Kassasbeh's influential tribe.

Solidarity demonstrations with the family are planned for nationwide after Friday's weekly Muslim prayers.

Abdullah cut short a US visit and returned to Amman Wednesday after the video of Kassasbeh's killing emerged.

"The blood of martyr Maaz al-Kassasbeh will not be in vain and the response of Jordan and its army after what happened to our dear son will be severe," he said afterwards.

On Wednesday, in response, Jordan executed two Iraqis on death row -- female would-be suicide bomber Sajida al-Rishawi and Al-Qaeda operative Ziad al-Karboli.

Abdullah travelled Thursday 120 kilometres (74 miles) south of Amman to Karak, where a traditional mourning tent was set up for Kassasbeh's family.

Hundreds of people gathered as the king sat next to the 26-year-old first lieutenant's father.

- 'Infidels and terrorists' -

Safi al-Kassasbeh branded IS "infidels and terrorists who know no humanity or human rights", and said the "international community must destroy" the group.

IS had offered to spare Kassasbeh's life and free Japanese journalist Kenji Goto -- who was later beheaded -- in exchange for Rishawi's release.

Rishawi, 44, was sentenced to death for her role in triple hotel bombings in Amman in 2005 that killed 60 people.

She was closely linked to IS's predecessor organisation in Iraq, and was seen as an important symbol for the jihadists.

Jordanian television suggested Kassasbeh was killed on January 3, before IS offered to spare him and free Goto in return for Rishawi's release.

Following the airman's capture, another member of the US-led coalition, the United Arab Emirates, withdrew from air strike missions over fears for the safety of its pilots, a US official said.

On Thursday, the US military said it was "repositioning some assets" to northern Iraq in a move designed to shorten the response time needed to reach pilots who end up in IS-held territory.

US President Barack Obama, who hosted King Abdullah in a hastily organised meeting before his return to Jordan, decried the "cowardice and depravity" of IS.

IS had previously beheaded two US journalists, an American aid worker and two British aid workers in similar videos. It has also killed a second Japanese hostage.

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