The advertising boom that has seen internet revenues grow at 60 per cent for the past three years could continue until 2008, a key search-engine marketing player has predicted.

A surge in search and directories advertising underpinned growth of 59 per cent to $684 million for the nine months to September, compared with the same period last year.

Search and directories advertising grew 70.5 per cent to $104 million in the September quarter compared with the same three months last year, outpacing the boom in classified and display advertising, which grew 50 per cent to $81 million and $78 million respectively.

Global search-engine marketing agency 24/7 Real Media said the official figures under-reported the size of the search market by $40 million in the last quarter alone by underestimating the money advertisers spent on dominant search engine Google, which does not disclose its actual numbers.

"There are clients in Australia that are spending more than $1million a month at the moment on search in Australia and there's no way for (the Audit Bureau of Verification Services) to track that," said 24/7 Real Media sales and marketing director Robbie Hills.

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