Google has asked a US Federal judge to extend the antitrust controls on Microsoft, which are due to expire in November.

The search giant said that Microsoft has been attempting to corner the desktop search market by allowing only its own software to be used in Vista. Microsoft later backed down and agreed to support third-party desktop searches. 

Google said that Microsoft's "hardwiring of its own desktop search product into Windows Vista violates the final judgment" in the US government's antitrust case against the software maker.

The move is unusual since Google could have appealed to the US Department of Justice, but instead went straight to the courts. This choice indicates that Google expected to get further in a legal case rather than by lobbying.