The internet will overtake magazines to become the world’s third-largest advertising medium by 2010, according to Steve King, chief executive of ZenithOptimedia. The head of the media-buying firm also believes that China will become the fourth-largest market for advertisers.

Mr King, who will be speaking at the 35th UBS annual media conference in New York today, will present an optimistic view of the future for advertising. He expects internet advertising to be worth $36 billion (£17.5 billion) this year, $5 billion more than predicted in December 2006. Global online advertising will increase by 24 per cent in 2008 and 69 per cent over the next three years (2007-10), reaching $61 billion in 2010, he will say.

A spokesman for Zenith said: “We predict global internet advertising to pass three milestones in the next three years: to overtake radio advertising in 2008; to attain a double-digit share of global advertising in 2009; and to overtake magazine advertising in 2010, with 11.5 per cent of total ad spend.”

Television will continue to dominate the global advertising market in 2010, with a predicted $198.89 billion in revenues, with newspapers next at £134.82 billion. Zenith forecasts that in 2010 the internet will account for $60.88 billion of total advertising spend, while magazines will account for $60.58 billion of expenditure.

Britain is one of the world’s most mature internet advertising markets, as it is one of only four places where internet advertising accounts for 15 per cent or more of total spend.

Zenith forecasts that by 2010 the internet will account for more that 20 per cent in the same four markets – which include Denmark, Norway and Sweden – and more than 15 per cent of advertising spend in ten other countries.

Mr King predicts that worldwide advertising expenditure will grow by 6.7 per cent in 2008, up from 5.3 per cent this year, as developing markets compensate for slow growth in developed countries.

The Olympic Games in Beijing and the US presidential election will contribute to the growth.

A spokesman for Zenith said: “While the credit squeeze is dampening economic growth around the world, we do not expect the advertising market to follow suit.”

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