Untrained told not to attempt kiss of life

But those lacking full skills should still give chest compressions, the best chance of saving a life, and not be afraid to use heart-start machines as well if necessary.

Cardio-Pulmonary Resuscitation (CPR) involves chest compressions and "rescue" breaths, with the aim of restarting the heart. While charities urge people to learn full CPR, guidelines say untrained members of the public should leave out the 'rescue breaths' and just give chest compressions if they are helping out in a crisis.

Experts have found people are reluctant to give mouth to mouth, with some unwilling to "kiss" a stranger and others concerned about getting the technique wrong.

The 2010 Resuscitation Guidelines published today by the Resuscitation Council said the first action should be dialling 999, and, even if someone is untrained, every opportunity should be taken to give chest compressions because "any CPR is better than no CPR".

People should perform chest compressions at a depth of 5cm to 6cm, at a rate of 100 to 120 compressions per minute.

An estimated 30,000 people each year in the UK have cardiac arrests in the community but fewer than 10 per cent survive and only around a third receive bystander CPR. But studies have shown that a bystander performing CPR can double the chances of the victim living.

The guidelines also recommend people use heart-start machines, called Automated External Defibrillators (AEDs), even if they are untrained.

Meng Aw-Yong, medical adviser at St John Ambulance, said: "Every year thousands of people die of cardiac arrest when first aid could have helped them live. Encouraging untrained members of the public to do chest compressions, as well as using an AED to try and restart the heart, could have a dramatic effect on the numbers surviving cardiac arrest.

"This is a great step forward in ensuring that more people are the difference between lives lost and lives saved."