Britain's Prince Charles has called on the public to stop taking baths.

The 61-year-old royal - who is well-known for his environmental advocacy - is urging British families to take short, five minute showers in a bid to protect the environment.

Snub the tub. If everybody in a four-person family replaced one bath a week with a five-minute shower, you could save between £5 and £15 per year off your energy bill.

The heir to the throne's instruction was part of 20 lifestyle changes listed in his new green campaign, Start.

His campaign message says: "Snub the tub. If everybody in a four-person family replaced one bath a week with a five-minute shower, you could save between £5 and £15 per year off your energy bill."

But critics say he should extend his washing advice to the royal family, as his father the Duke of Edinburgh is known to enjoy a bath.

The queen's husband, 89, badly bruised his eye after catching it with his thumb after slipping in the tub in 2005 while Charles' former sister-in-law Sarah Ferguson also admitted to taking ice-cold baths to alleviate her "dark moods".

Meanwhile, Prince Charles is taking his green message across Britain in an eco-friendly tour.

The royal is to promote his new project Start - which campaigns for "sustainable living - in a five-day tour where he will meet ethical fashion designers, guerilla gardeners and eco-obsessed pensioners, as well as launching his own green initiatives.