Britain is to become the first country in the world where the erectile disfunction drug Viagra can be bought without the need for a doctor's prescription from 2018, its maker Pfizer said.

The US pharmaceutical giant made the announcement late on Tuesday, saying it had received authorisation from the British regulator following a public consultation.

The hope is that men who have not previously sought help will now be more likely to do so, although men with heart problems or taking "interfering medicines" will still need a prescription to purchase Viagra.

Officials also hope that the decision will avoid purchases of Viagra on websites operating illegally.