E-cigarettes containing nicotine could increase the risk of heart attacks and strokes, according to a new study.

The study by a team of scientists in Stockholm found vaping devices containing the stimulant could cause an increased heart rate and blood pressure, as well as stiffening of the arteries.

Scientists recruited 15 healthy volunteers, who had never used e-cigarettes, to take part in the experiment.

Tests found in the 30 minutes after smoking the e-cigarettes containing nicotine, there was a significant increase in blood pressure, heart rate and arterial stiffness.

There was no effect in the volunteers who smoked the e-cigarettes without nicotine.

Dr Magnus Lundback, of the Karolinska Institute, said: "The number of e-cigarette users has increased dramatically in the last few years. E-cigarettes are regarded by the general public as almost harmless.

"The e-cigarette industry markets their product as a way to reduce harm and to help people to stop smoking tobacco cigarettes. However, the safety of e-cigarettes is debated, and a growing body of evidence is suggesting several adverse health effects.”

While the effects seen in the tests were temporary, Dr Lundback said explained chronic exposure to e-cigarettes with nicotine could cause permanent effects on arterial stiffness in the long term.

He added: "The results are preliminary, but in this study we found there was a significant increase in heart rate and blood pressure in the volunteers who were exposed to e-cigarettes containing nicotine.

“Arterial stiffness increased around three-fold in those who were exposed to nicotine containing e-cigarettes compared to the nicotine-free group."