ZenithOptimedia said new forms of online advertising such as search and datafeed, coupled with more effective ways of measuring it and tracking consumers' responses, were making the medium more attractive.
ZenithOptimedia Group forecasts that internet ad expenditure will grow 76% between 2005 and 2008, while adspend in other media will grow by substanially less. Radio is to grow by 10% and cinema by 27%.
In its latest foreceast ,the media agency says that the pace of development has caused it to upgrade its forecasts yet again.
"We now forecast the internet to account for 7% of worldwide ad expenditure by 2008, up from our 6.5% forecast in April and 6.0% in December."
Internet expenditure accounted for 4.7% in 2005 and ZenithOptimedia expects it to overtake outdoor this year, a year earlier than it predicted three months ago.
The figures were released as part of new research that showed that the UK and Germany are expected to show the lowest increase in adspend in Europe as a result of the World Cup.
ZenithOptimedia says that it expects the growth in the UK's advertising economy to be a relatively poor 1.2%, with the German advertising market expected to grow by 1.6% as a result of the tournament.
It has attributed the relative lacklustre performance to the fact that ITV1 has to share the tournament with the publicly funded BBC.
The media agency said that, as well as having to share the tournament with the BBC, ITV1 has been hit by a decline in viewing caused by the spread of digital television.
ZenithOptimedia said that the channel has not been able to extract the premium prices it would normally expect for World Cup viewers.
In the case of Germany the agency said that some of the extra growth in the ad market could be attributed to football-themed campaigns in print, online and outdoor.
However, most of the matches have been shown on Germany's public channels, which are permitted to sell very little airtime, so advertisers have not been able to make much use of the television coverage.
The agency expects advertising revenue growth in Germany using television to decline slightly in 2006 to 1.5% this year from 1.8% in 2005.
In the US, ZenithOptimedia says it expects a mild upturn in the advertising market on the back of the World Cup, but that it was more confident that the US would see an upturn due to the run-up to the mid-term US elections in November.
In Asia, extra revenues stimulated by the World Cup in Asia had been particularly prevalent in Malaysia and South Korea.
The agency said it expects global advertising spend to be up by 6.1% worldwide in 2006, slightly upgraded from the 6% rise predicted by the group in April this year. ZenithOptimedia also predicted that the global advertising economy would expand by 5.3% in 2007 and 5.6% in 2008.
Advertising spend on the internet is also expected to overtake the spend on outdoor globally during 2006.
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