Google's $3.1 billion acquisition of online advertising specialists DoubleClick is in doubt today, following a chorus of complaints against the deal.Microsoft, who was among the losing bidders for DoubleClick, is joining forces with communications giant AT&T to try and block the final sale being ratified.
The companies fear that the new deal will bequeath Google a virtual monopoly over the online advertising market.
Jim Cicconi, senior executive vice-president of external and legislative affairs at AT&T, complained that "Google is acquiring its only substantial competitor, thereby positioning itself as the sole broker of internet advertising".
Mr Cicconi urged that "this merger be stringently reviewed by regulators".
Microsoft general counsel Brad Smith called for the deal to undergo "scrutiny from regulatory authorities to ensure a competitive online advertising market".
Google, however, dismissed such criticism.
"The advertising market is extremely competitive and dynamic", a spokesperson told the Independent.
The company insists that with or without DoubleClick, Google serves only a tiny fraction of the market.
A Jupiter research project - reported by eConsultancy - had recently suggested that Google's dominance of the online advertising market was under threat.
The research showed Google with 17 per cent of all such business in 2006 and Yahoo! with 16 per cent.
The Microsoft Network received seven percent of all online advertising revenue last year, according to the report.
