The world's leading search engine Google will account for over a quarter of all web advertising revenues in the US before the end of 2006, according to the predictions of the online marketing research company eMarketer.

Despite the efforts of nearest industry rival Yahoo to reign in Google's market dominance through a series of diversification initiatives, the company is soon expected to be racking in a full $4 billion from online ads.

Only 12 months ago the two giant search engine firms recorded equal web marketing profits of around $2.4 billion, but Yahoo is expected to achieve a relatively limited growth rate 17.5 per cent this year, reports e-consultancy.

eMarketer senior analyst David Hallerman is quoted as saying: "Google's markedly better than Yahoo and other rivals at squeezing more revenue for itself from the advertising it serves up.

"Also, Google's reputation as the online ad leader makes it more of a first choice for businesses trying out online advertising for the first time."

Despite some scepticism surrounding the profit potential of YouTube, the video-sharing company recently purchased by Google, the search engine is convinced its web advertising expertise will make the $1.6 billion investment a worthwhile endeavour.