Syrian President Bashar al-Assad has said US-led air strikes have only increased his resolve to continue “fighting and crushing” rebel forces in the country.

He was speaking hours after the US, France and the UK carried out missile attacks in response to his alleged use of chemical weapons in the city of Douma.

Assad said he would not change his course of fighting "terrorists in every inch of the nation”, according to the Reuters news agency.

Earlier, the Syrian government had posted a video online appearing to show the president arriving for work in the capital Damascus.

Footage shows Assad wearing suit and tie and carrying a briefcase as he walks into a marble-floored building.

Syrian president Bashar Al-Assad releases footage of him walking into work hours after air strike

It was captioned “the morning of resilience” and circulated on the presidency’s social media feeds.

The show of defiance came as hundreds of Syrians gathered in squares across the capital in support of the regime.

Men and women waving Syrian flags – as well as those of allies Russia and Iran – were seen in film captured by the AP news agency.

Syria air strikes: US, UK and France joint military action Show all 21 1 /21 Syria air strikes: US, UK and France joint military action Syria air strikes: US, UK and France joint military action A picture released by the French Defence audiovisual communication and production unit (ECPAD) shows the launching of a cruise missile from a French military vessel in the Mediterranean sea towards targets in Syria overnight. The United States, France and Britain carried out a wave of punitive strikes against Bashar al-Assad's Syrian regime in the early hours of April 14 in response to alleged chemical weapons attacks. AFP/Getty Syria air strikes: US, UK and France joint military action Rafale warplanes being prepared for take off at the Saint-Dizier aerial military base, eastern France. Media reports state that the United States, France and Britain launched military strikes in Syria to punish President Bashar Assad for an apparent chemical attack against civilians and to deter him from doing it again. EPA Syria air strikes: US, UK and France joint military action Damascus skies erupt with missile fire as the US launches an attack on Syria targeting different parts of the capital. President Donald Trump announced airstrikes in retaliation for the country's alleged use of chemical weapons. AP Syria air strikes: US, UK and France joint military action A map show the location of the air strikes carried out by the US-led coalition in Syria overnight. US Department of Defense Syria air strikes: US, UK and France joint military action The wreckage of a building described as part of the Scientific Studies and Research Centre compound in the Barzeh district, north of Damascus. AFP/Getty Syria air strikes: US, UK and France joint military action Royal Air Force tornado jets take off in the early hours from RAF Akrotiri airbase in Cyprus to conduct air strikes in Syria. Four Tornado jets fired Storm Shadow missiles "at a military facility -- a former missile base -- some 15 miles (24 kilometres) west of Homs, where the regime is assessed to keep chemical weapon precursors," the defence ministry said in a statement. AFP/Getty Syria air strikes: US, UK and France joint military action Map of where the air strikes hit in Syria released by the Pentagon. A Syrian military statement says the US, Britain and France fired 110 missiles during a joint attack on targets in Damascus and outside. Pentagon Syria air strikes: US, UK and France joint military action A photo released on the Twitter page of Hezbollah's "Central War Media" account shows night footage of flares above Damascus seen through a night-vision device as Western strikes reportedly hit Syrian military bases and chemical research centres in and around Syria's capital. US, France, and Britain announced the joint operation. AFP/Getty Syria air strikes: US, UK and France joint military action The preliminary damage assessment of Barzah research and development centre before and after the air strikes, released by the Pentagon. Pentagon Syria air strikes: US, UK and France joint military action The preliminary damage assessment of Him Shinshar chemical weapons bunker before the air strikes. Pentagon Syria air strikes: US, UK and France joint military action The preliminary damage assessment of Him Shinshar chemical weapons bunker after the air strikes. Pentagon Syria air strikes: US, UK and France joint military action The wreckage of a building described as part of the Scientific Studies and Research Centre compound in the Barzeh district, north of Damascus. AFP/Getty Syria air strikes: US, UK and France joint military action The wreckage of a building described as part of the Scientific Studies and Research Centre compound in the Barzeh district, north of Damascus. AFP/Getty Syria air strikes: US, UK and France joint military action The wreckage of a building described as part of the Scientific Studies and Research Centre compound in the Barzeh district, north of Damascus. AFP/Getty Syria air strikes: US, UK and France joint military action The preliminary damage assessment of Him Shinshar chemical weapons storage site before and after the air strikes, released by the Pentagon. Pentagon Syria air strikes: US, UK and France joint military action The preliminary damage assessment of Him Shinshar chemical weapons storage site before the air strikes. Pentagon Syria air strikes: US, UK and France joint military action The preliminary damage assessment of Him Shinshar chemical weapons storage site after the air strikes. Pentagon Syria air strikes: US, UK and France joint military action A British military Typhoon aircraft lands at the Sovereign Base Area (SBA) of Akrotiri, a British overseas territory located ten kilometres west of the southern Cypriot port city of Limassol, following US, British and French strikes on Syria. Syrian state media slammed Western strikes on Saturday as illegal and "doomed to fail," after the US, Britain and France launched a joint operation against the Damascus.government. Huge blasts were reported around the Syrian capital, moments after the three Western governments announced they were striking Syria's chemical weapons capabilities. AFP/Getty Images Syria air strikes: US, UK and France joint military action The preliminary damage assessment of Him Shinshar chemical weapons bunker before and after the air strikes, released by the Pentagon. Pentagon Syria air strikes: US, UK and France joint military action The preliminary damage assessment of Him Shinshar chemical weapons bunker before the air strikes. Pentagon Syria air strikes: US, UK and France joint military action The preliminary damage assessment of Him Shinshar chemical weapons bunker after the air strikes. Pentagon

In scenes which appear to have an almost carnival-like atmosphere, posters of Assad are waved, car horns are honked and victory signs are flashed by government supporters.

“We are not scared of the American missiles, we humiliated its missiles, we are in the streets, in the squares, we are not in shelters,” says one protestor Mahmoud Ibrahim. “They laughed on them."

Another, Abdulhamid Salhab said the one-hour bombing – which included use of Britain’s bunker-busting Storm Shadow cruise missiles – would “not affect the steadfast of the Syrian Arab people and will not affect the morale of the brave Syrian Arab Army."

A few hours earlier loud explosions jolted Damascus and the sky turned orange as Syrian air defence units fired surface-to-air missiles in response to three waves of military strikes meant to punish Syrian President Bashar Assad for his alleged use of chemical weapons last week.

The western allies said the strikes were precision hits aimed specifically at destroying the regime’s chemical weapon facilities.