Forty million Americans rely on the internet as their primary source for news and information about science, research suggests.

The survey, conducted by the Pew Internet and American Life Project, found that a fifth of US people online turn to the web for most of their science news.

The internet is second only to television, which is the main source for 41 per cent of Americans, while newspapers and magazines came in joint third.

One third (33 per cent) of home broadband users say they get most of their science news and information from the television, while 34 per cent prefer the internet.

Among adult home broadband users under the age of 30, the internet is the most popular source for science news.

Some 44 per cent of those between the ages of 18 and 29 say they get most of their science news from the net, while just 32 per cent use the television.

Study author John Horrigan said: "People's use of the internet for science information has a lot to do with the internet's convenience as a research tool, but it also connected to people's growing dependence on the internet for information of all types.

"Many think of the internet as a gigantic encyclopedia on all subjects and this certainly applies to scientific information."

Popular science-related sites included NationalGeographic.com, Nasa.gov, Science.com and Nature.com.

The survey questioned 2,000 US adults during the first five weeks of 2006.

Market research firm Princeton Survey Research Associates did the poll for the Pew Internet and American Life Project.