RAF jets were unleashed above Iraq on Saturday as Britain threw its military might behind a US-led air war against the rampant Islamic State (Isis) terror group. As two Tornado jets took off from RAF Akrotiri in Cyprus, David Cameron said Britain was playing its part in an international coalition aimed at destroying the "appalling terrorist organisation". The Ministry of Defence said the RAF jets, loaded with laser-guided bombs and missiles, were equipped with the capability to perform an attack role.

After the jets returned to base seven hours later, the MoD said their first combat mission had not engaged any targets. Officials said the sorties had, however, gathered "invaluable intelligence" in the quest to degrade Isis's infrastructure. "Although on this occasion no targets were identified as requiring immediate air attack by our aircraft, the intelligence gathered by the Tornados' highly sophisticated surveillance equipment will be invaluable."

The MoD also revealed that RAF transport aircraft had delivered fresh supplies to the Kurdish authorities to bolster their efforts to defeat Isis.

The British entry into the war on Isis came less than 24 hours after MPs voted by 524 to 43 in favour of approving air strikes against Isis targets in Iraq, the first such military action in the country since British troops were pulled out of Basra in May 2009. Many MPs expressed fears about rejoining military action in the region, while others raised doubts over why the Commons was not giving its backing to similar strikes on targets in Syria, where Isis is mainly concentrated.

Six Tornado jets have been based in Cyprus since last month but had been restricted to reconnaissance flights. The RAF also has a Rivet Joint spy plane in the region, which is stepping up surveillance efforts to identify potential targets, while intelligence will also be sought from Iraqi and Kurdish forces on the ground. "There are moving targets obviously – convoys of Isis fighters whom we can identify with the surveillance that we are going to intensify," defence secretary Michael Fallon said.

The Tornados joined the US air force and jets from regional states in flying rotations over the north and centre of Iraq while targets were nominated for them to strike. A small number of SAS troops have been on the ground with US special forces for more than a month helping select targets and guide in bombs.

Britain entered the fray more than seven weeks after the US first sent fighter jets to defend the Kurds of northern Iraq from an Isis advance and one week after France, Saudi Arabia, the UAE, Bahrain, Jordan and Qatar sent their air forces to attack targets inside Syria. Denmark and Belgium have also committed their air forces to tackling Isis, but, like Britain and France, have limited their roles to inside Iraq. Isis controls a swath of land from the eastern edge of Aleppo to north-west Iraq and the northern fringes of Baghdad, where its influence continues to jeopardise Iraq's new government.

Iraq had implored its allies to send forces after its military was humiliated when Isis seized the country's second biggest city, Mosul, on 10 June, Tikrit the next day, and then narrowly lost a race with the Kurds to seize Kirkuk.

On Friday, Cameron gave no indication of how long the RAF would remain involved and said he was undecided about whether to extend the mission to Syria, despite the now redundant border between the two states that gives Isis unfettered access across western Iraq and eastern Syria.

In Isis-run Mosul, which has been battered by air strikes for the last month, locals seemed mostly wary of Britain's involvement. Some, however, welcomed the move. "We agree with Britain bombing Isis," said a man who identified himself as Saleh, 42, a doctor. "We hope that either the US or British military kill all Isis members because life in Mosul is not good. There is no electricity, no water and … everything is so expensive."

Mohammed, 37, a media worker from Mosul, feared civilians would pay a heavy toll. "The problem now is how to distinguish between civilians and militants especially in a city of two million people. When fighting starts, moving around Mosul will be very dangerous. Essential services will surely stop – electricity, water supply, fuel and hospitals."

In the last three months, the Isis advances have changed the face of the Middle East, forcing the evacuation of close to half a million people from the Nineveh plains in north-western Iraq and from north-eastern Syria, where minorities, including Christians, Yazidis, Turkmen and Kurds, have been forced to leave.

On Saturday US jets attacked Isis positions south of the Syrian Kurdish town of Kobani for the first time in an attempt to stop a militant push that has led to more than 150,000 Kurds fleeing across the border to Turkey in the last week. The US and Arab state air forces have been flying missions inside Syria since last Monday that they claim are aimed at slowing Isis's momentum and degrading its capabilities.

Additional reporting: Fazel Hawramy