Fears that online news would render irrelevant traditional outlets such as television and print newspapers have not come true, a study has found.

Online news sites have become a complementary and convenient tool, but are not used by their slowly growing audience to read in-depth articles, The Pew Research Centre For The People and The Press said in a report released on Sunday.

Currently, 31 percent of US residents check the web for news at least three days per week, up from 29 percent in 2004 and 23 percent in 2000, a modest growth rate after explosive adoption in the late 1990s.

Americans generally turn to news sites for quick, convenient scanning of articles, not for detailed, in-depth information, according to the 125-page study, entitled Maturing Internet News Audience: Broader Than Deep.

"The web serves mostly as a supplement to other sources rather than a primary source of news," reads the report, which the organisation conducts every two years.

People spend an average of 32 minutes getting news online one any particular day, less than they devote to news on television (53 minutes), radio (43 minutes) and print newspapers (40 minutes).

"Those who use the web for news still spend more time getting news from other sources than they do getting it online. In addition, web news consumers emphasise speed and convenience over detail," reads the report.

Contrary to earlier predictions, the convenience of getting news online hasn't increased overall news consumption among US residents. "The percentage of Americans who skip the news entirely on a typical day has not declined since the 1990s. Nor are Americans spending any more time with the news than they did a decade ago," the report says.

Regarding blogs, a medium which has attracted much attention among news outlets in recent years, only 4 percent of US residents regularly read those devoted to discussing news events.