The fast-boil and illuminated models now on the market are likely to use more energy than the previous generation, according to research commissioned by the government.

As kettles account for almost one-third of the electricity used by cooking appliances in the home - with seven million sold in the UK each year - environmental groups are warning this will lead to greater production of the greenhouse gases associated with global warming.

DEFRA, the Department for Environment, Food and Rural Affairs, has produced a briefing note on the electrical consumption of the new kettles as part of a market transformation programme (MTP) series on reducing energy consumption.

It says the increase is due to new features and design changes which include larger kettle capacities. This means users habitually over-fill them by a greater amount and use more energy to boil them. There is also a trend towards wider bases so more water is needed to cover the element. Some kettles are therefore unable to boil only a single cupful. Faster boiling times may also result in more energy consumption as consumers are less concerned about over-filling the kettle because it does not take as long to boil, the MTP report says.

Other increasingly common additional features which raise energy use include keep-warm facilities to have hot water on standby and illumination of displays. The MTP report says that an "eco-kettle" developed by UK firm Product Creation could save consumers 30% of energy compared with their normal kettle although the initial cost is more expensive. Its key feature is a button that allows the user to choose exactly how much water to boil.

Stuart Hay, head of research for Friends of the Earth Scotland said: "The humble kettle may seem harmless enough. But collectively they can account for a significant proportion of the electricity consumed in this country. "The fact that kettles are becoming increasingly inefficient is symbolic of just how wasteful society is becoming when it comes to the energy we use. Action needs to be taken to encourage the manufacture of less energy-wasting designs. "People are concerned at rising energy prices yet many of us continue to fill their homes with appliances that quietly consume ever increasing amounts of electricity."