An internal report by the Road Safety Authority has found that 30% of people who died in road crashes in Ireland in 2013 had taken prescription medicine.

The report, obtained by RTÉ News under the Freedom of Information Act, found that prescribed sedatives are almost as common as alcohol in road deaths.

The report examined 109 coroners' reports from 2013.

It found that while 31% of the people who died in road crashes that year had taken alcohol, 30% had taken prescription medication, and toxicology reports also revealed that 20% had taken illegal drugs.

Benzodiazepine, a sedative-hypnotic drug that slows down the body's functions, was the most common prescription drug found in the toxicology reports.

There is no indication whether the people who took this drug were prescribed it, or obtained it on the black market.

The Medical Bureau for Road Safety said motorists who take prescription medication in accordance with their doctor's advice should have no concerns about driving.

Gardaí have warned that anybody whose driving is impaired by any intoxicant, including prescription medication, can be prosecuted.