While many people may be keen to do their bit for the environment by purchasing low-energy printers and recyclable ink cartridges, they could be wasting large amounts of money and energy by leaving portable gadgets on charge at home.

According to a study conducted by E.ON, the UK spends £134 million more than necessary each year on power for devices that have been left plugged in when their battery is full.

One in five people said they did this because they are worried about running out of power when on the move, while ten per cent admitted they were too lazy to unplug their items.

Laptops are the most commonly overcharged item, with 43 per cent being left on after they are at full power, followed by mobile phones (41 per cent) and iPods (ten per cent).

Spokeswoman for E.ON Emma Thompson said: "Generally, mobile phones only take two hours to charge but most people leave them plugged in overnight."

Recently, the Press Association reported claims by researchers at the University of Salford that electrical items left on charge or standby could cost an average homeowner £150 a year in energy bills.