Britain is intensifying its involvement in Iraq by flying military equipment on behalf of Jordan to Kurdish forces fighting Islamic State (Isis) jihadists in northern Iraq and despatching a fleet of Chinook helicopters to airlift Yazidi refugees besieged on Mount Sinjar.

Hours after the Kurdish security chief Masrour Barazani pleaded with Britain to rally to the help of the Kurds, the government's emergency committee Cobra agreed to transport Jordanian military trucks to Irbil.

The move comes amid growing pressure on David Cameron to launch military strikes against the extremists, as former Thatcher ally Conor Burns warned that Isis forces "want a holocaust".

Some Conservative MPs privately criticised the prime minister for failing to cut short his holiday in Portugal to return home to take charge of the government's response to the crisis.

The Cobra meeting, chaired by the foreign secretary Philip Hammond, also agreed to deploy Chinook helicopters to land on Mount Sinjar to airlift some of the thousands of Yazidi refugees who fled Isis forces. The deployment of the Chinooks marked a significant escalation of Britain's military involvement in the humanitarian mission in northern Iraq which has been limited until now to dropping supplies of water and solar lanterns from RAF C130 Hercules aircraft.

Hammond told the Cobra meeting that an emergency meeting of EU foreign ministers may be held to agree to arm the Kurdish forces leading the fight against Isis. It is understood that France and some of the new EU member states in eastern Europe are keen to arm the Kurdish forces amid fears that Isis presents a strategic threat both to the region and to Europe.

Britain has some sympathy for the French view though the government may not join in arming the Kurds amid signs that that may be a step too far for the Liberal Democrat side of the coalition. Hammond is understood to have made clear that the increased British involvement in Iraq does not amount to classic "mission creep" because it is wholly consistent with the government's stated objective of providing humanitarian assistance and of helping to defeat Isis forces short of direct military involvement.

The British decision to fly Jordanian military equipment to the Kurdish forces in northern Iraq followed a plea by Barazani for Britain to arm the Kurds against the Isis forces now menacing Irbil. He warned that failure to do so is certain to amplify the terror threat at home.

In an interview with the Guardian, Barazani implored the British public not to allow fatigue from more than a decade of war to stop support for the Kurds in what is fast shaping up to be the biggest threat to Iraqi Kurdish society since the collapse of the Ottoman empire almost 100 years ago.

"In terms of drawing the lines [the regional borders], the UK had the greatest role in the creation of the modern Middle East," he said. "Now is not the time to say it is not our problem. I would like Britain to remember that we are not Helmand, or Basra, we are your friends.

"For how long do the Kurds have to pay the price of the mistakes that were made. We are victims of Sykes Picot," he said of the British-French agreement that enshrined the modern states of Lebanon and Syria, and led to the creation of Iraq's current borders. "For how long do we have to be held hostage, or to be vulnerable. The international community needs to find a solution for the Kurds.

"Everybody underestimated the strength, the role and the agenda of Isis and is now regretting it, said Barazani. "This is an organisation that does recognise any legitimate border, or tolerate plurality. It rejects everything else beside itself."

For the past 10 days, Kurdish forces have been battling an Isis advance on the north that quickly consumed areas dominated by minority groups on Iraq's Nineveh plains. The speed of the advance and the strength of the weaponry used has stunned the autonomous enclave and led to the US supplying weapons in recent days to outgunned Kurdish troops and launch airstrikes against jihadist positions.

Barazani spoke out as Downing Street faced pressure to join the US in launching military strikes. Burns warned that Isis forces "want a holocaust of everyone who does not share their brutal ideology".

Downing Street insisted that the government is not contemplating military action. But three Tory MPs who opposed the planned military strikes against the regime of the Syrian president Bashar al-Assad last year, indicated support for action in Iraq. Dr Julian Lewis, a member of parliament's intelligence and security committee, Nick de Bois and Dr Phillip Lee all called for parliament to be recalled.

Lewis told the Guardian: "The government was proposing last year to take military action to overthrow an appalling dictator with no guarantee that our deadly enemies from al Qaida would not be successful in taking his place and if they did so they would inherit a ready made stock of the very sorts of deadly chemical weapons we had gone to war in Iraq in the mistaken belief that we were trying to keep those from getting into extremists' hands. This is a totally different situation in Iraq. Far from assisting our deadly enemies to get more power this would be a question of assisting the people of the region to resist our deadly enemies who have a totalitarian, extremist death cult and possess an ideology that is a direct threat to western values and civilisation."

Alistair Burt, a former Middle East minister, warned that Isis jihadists must be "killed soon" as he voiced support for arming Kurdish forces. Describing the Isis forces as "fascist and lawless bandits" that must be defeated by military action, Burt told the Guardian: "You have to eliminate IS [Isis]. These people will not go to the negotiating table in Geneva. These people have to be killed and have to be killed soon."

Senior Tories say that Cameron's defeat in last year's vote, during an emergency recall of parliament at the end of August after Assad's forces launched a chemical weapons strike against a Damascus suburb, helps explain his reluctance to join the US in launching air strikes against Isis forces. George Osborne advised the prime minister after the vote that it would be all but impossible to secure parliamentary support for future military interventions during the current parliament because of a sizeable contingent of Tory MPs opposed to intervention and a belief in No 10 that Ed Miliband acted in a duplicitous manner.

"David Cameron and George are leery about relying on Ed Miliband," one senior Tory said.

But Tories also say that the Cameron is mindful of public opinion which is wary of military intervention. A ComRes poll for ITV News found overwhelming support (84%) for supplying humanitarian aid to Iraqi civilians trapped on Mount Sinjar. It found that more people (45%) support airstrikes against Isis forces than oppose such action – 37%. But the poll found that voters are overwhelmingly opposed to sending in British troops – by 63% to 18%.

Sir Menzies Campbell, the former Liberal Democrat leader, warned of "incalculable" consequences if Kurdistan fell to Isis. He told The World at One on BBC Radio 4: "I am not persuaded at the moment that the UK should join in airstrikes along with the US. But one has to keep an open mind about that because circumstances change very rapidly. If the northern part of Iraq, what we colloquially refer to as Kurdistan, were to fall then the consequences in an already unstable region would be incalculable."