David Cameron is under fire for going on holiday again tomorrow after declaring he can run the government “by BlackBerry” while Britain is being dragged closer to military action against the Islamic State in Iraq.

The PM defended his decision to go on his annual family holiday with his wife Sam to Cornwall – less than a week after returning from a 10-day break in Portugal – saying he would still be able to run the country with his smartphone.

Many voters may think it right he insists on going on holiday during August. But he faced a range of hostile headlines in the tabloid press and criticism from Labour MPs.

The Mirror headline screamed: Cameron Under Fire For Taking ANOTHER Holiday While Britain Is Dragged Into Iraqi Crisis and The Sun questioned whether it was right to disappear again so soon after proclaiming the Islamic State "a monstrous threat".

PM gives up holiday as UK executioner raises stakes

In the face of such criticism, Cameron said: "Wherever I am in the world, I am always within a few feet of a BlackBerry and an ability to manage things should they need to be managed.

"And indeed as I have done on I think almost every holiday that I have enjoyed over the past few years, I am able to return instantly should that be necessary."

He added: "For the next few days I shall not be terribly far away so, if that’s necessary, you will find me at my desk."

When Tony Blair was PM, he used to leave his deputy, John Prescott, in charge when he took a holiday, which caused even more uproar in the tabloids. But Cameron is not prepared to leave Nick Clegg, the Lib Dem deputy leader, holding the reins. "I always make sure there are senior ministers on duty in Westminster but I don’t hand over the government to a deputy," he confirmed yesterday.

The Camerons make an annual pilgrimage to Polzeath in Cornwall with their children. The youngest, Florence,was born at the Royal Cornwall Hospital, Truro during their 2010 Cornish break.

Labour leader Ed Miliband is on holiday in France but that did not stop sniping at Cameron by Labour MPs. Labour's John Mann said: "Government by BlackBerry is not any kind of government. We have British troops in Iraq and I find it extraordinary people become Prime Minister then act like Joe Public."

The former envoy on human rights in Iraq, Labour MP Ann Clwyd, said Cameron's decision to travel to Cornwall at such a critical time was “ridiculous”. She said it was a “very poor show” and seriously undermined the office of the Prime Minister. "I can’t believe he has pushed off if he thinks Islamic State is such a threat," said Clwyd.

There are some unanswered questions left hanging in the air as Cameron packs his bags:

Will the SAS be allowed to fire on IS? The Government has admitted that SAS troops are operating inside Iraq despite Cameron’s commitment that there will be “no boots on the ground”. What happens if the SAS ask to take part in military action on the ground, while the PM is in Cornwall? Won’t that break Cameron’s public promise not to get engaged in a ground war?

What are the rules of engagement for the RAF Tornados that are now flying military intelligence missions deep into Iraq? They are not supposed to be involved in air strikes like the US, but would the RAF jets be permitted to fire on IS forces if they saw them attacking refugees?

Ministers can duck these questions because Cameron is refusing to recall Parliament to debate the crisis before MPs are due back anyway on 1 September.

Meanwhile, the forecast for Polzeath for the rest of the week is 16C – and cloudy.