Microsoft's rivals are again putting pressure on the European Commission to take a hard line as it nears a decision on its antitrust case against the software giant.

The US-based Computer & Communications Industry Association (CCIA), a coalition of 30 technology companies, is calling for the Commission to force the break-up of Microsoft's Windows operating system.

In an article in the Financial Times Ed Black, chief executive of the CCIA, claimed that European antitrust laws would be undermined by a failure to take action against Microsoft.

"If [antitrust law] is to really have a meaning for the IT industry then a meaningful decision in this case is essential," he said.

CCIA members include familiar Microsoft foes Oracle, Sun Microsystems and AOL, as well as Nokia, Fujitsu, Yahoo, Nortel and Giga Information Group.

The Commission is believed to be close to reaching a decision following a four-year antitrust inquiry into Microsoft.

If found guilty, the company could be forced to un-bundle some software from Windows, and may face a fine of up to 10 per cent of its global revenues.

But Horacio Gutierrez, European lawyer for Microsoft, told the Financial Times that such a decision would severely harm the company's ability to operate and could be damaging to consumers.

"These competitors would not be satisfied with any remedy that stopped short of stopping Microsoft's ability to innovate," he said.