Iceland is urging tourists to stop buying environmentally damaging plastic bottles of mineral water as they are "wildly over-priced" and pointless in a country with some of the cleanest tap water in the world.

The Icelandic environment agency wants tourists to ditch single-use plastic and buy reusable water containers, amid concerns that the country's surge in popularity is putting undue strain on the environment.

The Nordic country has a population of just 300,000, but the number of foreign visitors has quadrupled in just six years, with 2.1 million people making the trip in 2017.

"With increased tourism, we need to do better at informing our guests about the water quality of tap water in Iceland, with the main achievement being the reduction of unnecessary plastic consumption," an environment agency spokeswoman told the Telegraph.

"People are buying water in bottles because they are not sure about the quality of water in Iceland. The aim...is to point out that once you have a bottle, you can just keep refilling it.

"Hopefully the initiative will also raise awareness among tourists and Icelanders about the unecessary plastic pollution connected to the consumption of still water and encourage consumers to bring a reusable bottle along when they are on the move."