It may even help people who have undergone open heart surgery or heart transplants.

But British experts have warned patients not to try to drink alcohol if they think they may be having an attack, as booze could react badly with other medication given to patients when they arrive at hospital.

Heart attacks happen when an artery feeding blood to the muscle is blocked and starves it of oxygen. If tissues do not get enough oxygen over a sustained period, cells begin to die - and send out messages which kill neighbouring cells as well.

Working with rats, researchers at Stanford University in California found that small amounts of alcohol could prevent the dying cells encouraging their neighbours to commit suicide.

The overall damage caused to the rats was reduced by 70%.

"We need to determine if it is true for humans, but this is not an outrageously high level of alcohol," said Dr Daria Mochly-Rosen, who led the study.

"This is the first study to show that a brief exposure to levels of alcohol that are really tolerated well -- even for those worried about addiction -- provides protection."

Benefits of alcohol

Other studies have already shown that a moderate alcohol consumption provides some protection against heart disease.

The alcohol dose protected cells against the damage caused by oxygen starvation by turning on a chemical called epsilon protein, it was reported in the Proceedings of the National Academy of Sciences.

This protected heart cells grown in a laboratory dish, and mice genetically engineered to produce the protein suffered less damage from oxygen starvation to their hearts than normal mice.

Dr Mochly-Rosen said: "People cannot predict when they will have heart attacks, but during open heart surgery and heart transplants similar damage can occur.

"Perhaps patients could be given intravenous alcohol - or whatever drug might be developed from the findings - just before the operation", she suggested.

Confusing message

However, a spokesman for the British Heart Foundation said that the message from the study might confuse the public.

He said: "We are advising caution. It is an interesting finding but needs much more research to clarify it. At the moment, we are concerned that people should not drink alcohol if they think they are having a heart attack.

"When they get to hospital they will be given drugs which could dangerously interact with it."

Earlier this month, Texas researchers found that a combination of alcohol and caffeine could help limit similar damage from stroke in lab rats.