Clocking up extra hours in the office can increase the risk of heart disease, a new study has found.

People who work an 11-hour day compared to those who work a standard seven or eight hours increase their risk of heart disease by 67%, researchers at UCL (University College London) discovered.

Researchers, who published their findings in Annals of Internal Medicine, said that information on working hours could be useful to GPs when calculating a patient's risk of heart disease alongside other indicators such as blood pressure, diabetes and smoking habits.

The research tracked 7,095 British civil servants aged between 39 and 62 for 11 years.

Over the course of the study, 192 participants suffered a heart attack. People who worked 11 hours or more a day were 67% more likely to have a heart attack than those who worked shorter hours.

Professor Mika Kivimaki, who led the research, said: "We have shown that working long days is associated with a remarkable increase in risk of heart disease.

"Considering that including a measurement of working hours in a GP interview is so simple and useful, our research presents a strong case that it should become standard practice.

"This new information should help improve decisions regarding medication for heart disease. It could also be a wake-up call for people who overwork themselves, especially if they already have other risk factors."

Professor Stephen Holgate, chairman of the Medical Research Council's (MRC) Population and Systems Medicine Board, said: "This study might make us think twice about the old adage 'hard work won't kill you'.

"Tackling lifestyles that are detrimental to health is a key area for the MRC, and this research reminds us that it's not just diet and exercise we need to think about."

Professor Peter Weissberg, medical director at the British Heart Foundation, added: "These most recent findings raise the possibility that long working hours may increase the risk of a heart attack. But further studies are required to confirm this association and clarify how it might be used to change our current approach to assessing someone's risk of developing heart disease and what advice we give on working conditions."