The Health Products Regulatory Authority has issued a warning over tanning injections which are being bought illegally over the internet.

The warning follows a sharp increase in the number of products seized in Ireland last year.

In 2015, 305 seizures were made, compared to just four in 2014 and five in 2013.

The HPRA says last year's figure related to one major seizure and an investigation is ongoing.

The products come in powder form and in some cases with a solution. They are mixed and injected into the stomach with an insulin needle.

The hormone in the injections, which can be bought online for as little as €40, encourages the production of melanin, making the skin turn brown.

However, the side effects can be serious, including nausea, depression and cardiovascular problems.

The injections have also been linked to skin cancer and stroke.

The Irish Cancer Society has described the practice of tanning injections as "sheer madness".

The HPRA has urged people not to use the injections, and has advised anyone who has been using the product to stop immediately and contact their doctor.