The data, released to paying subscribers on Tuesday night but not yet made public, show Google's dominance of the worldwide market for Web search dipping slightly to 62.8 per cent in February from 63.1 per cent in January, said the analyst, who declined to be named, though Google gained share in the US market.

The overall volume of searches done through Google dropped in February to 5.86 billion from 6.14 billion, according to the data. The overall worldwide volume of searches also dipped.

'We are continuing to see deceleration in growth in Web search,' said Jefferies & Co analyst Youssef Squali. 'Google's month-over-month 5 per cent decline is a little surprising, but all of the major Web search names were down.'

Investors cull through comScore's monthly search data for clues to growth trends in Google's core business of online advertising tied to such Web searches and to watch for whether any of its rivals is managing to slow the Google juggernaut.

Mr Squali said that, with the Web search market appearing to mature, investor focus is shifting more to how well Web search providers such as Google convert searches into actual advertising viewership. ComScore data on growth in 'paid clicks', or the number of Web search ads viewed in February, are due to be released by comScore to clients on Thursday.

ComScore plans to release a summary of its February Web search trends report after the market close on Wednesday.

ComScore data show Google's US share among the top five Web search providers growing to 59.2 per cent in February from 58.5 per cent in January. Yahoo saw its US share dip to 21.6 per cent from 22.2 per cent month-to-month.

Microsoft Corp, the No 3-ranked US Web search provider, slipped to a 9.6 per cent share in February from 9.8 per cent in January. No 4 and No 5 ranked AOL, a unit of Time Warner Inc, and Ask.com, a unit of IAC InterActiveCorp, saw their positions hold steady at 4.9 per cent each.

Citigroup analyst Mark Mahaney said in a research note that growth in search queries performed on Google has decelerated in recent months and blamed the increasing maturity of the computer-based Web search market.

ComScore, which tracks online audiences in 20 major Internet markets around the world, estimated Web surfers performed 66 billion searches overall in December, 71.9 billion in January and 67.4 billion in February.

Google's 62.8 per cent market share of the worldwide market compares with 58.5 per cent in February 2007, according to comScore data. Similarly, Yahoo saw its global share drop to 11.9 per cent from 12.2 per cent in February from January.

Chinese Internet search leader Baidu.com slipped to 4.5 per cent globally from 4.6 per cent in February from January while Microsoft's share was steady at 3.1 per cent. -- REUTERS