Microsoft has filed another batch of technical information with the EC (European Commission) in an effort to avoid an increase in fines resulting from a 2004 antitrust ruling against the company, an EC spokeswoman said today.

On 12 July, the EC fined Microsoft €280.5m (about £192m) for not supplying the technical information about the communications protocols used by its workgroup server software requested in the antitrust ruling. The EC calculated the fine at €1.5m (£1m) per day for the period from 16 December 2005 to 20 June 2006 and warned the company that the daily fine could increase if it did not supply all the requested documentation by 31 July.

Since that warning, the company has supplied further documentation on the protocols, and the EC is analysing it to determine whether it is complete, said the spokeswoman. "I don't know when the analysis will be finished," she said.

"From today, Microsoft could face a larger fine of up to €3m [£2m] a day [if the EC finds the documentation lacking]."

In its March 2004 antitrust ruling, the EC ruled that Microsoft had abused its monopoly in desktop PC OS (operating systems) to gain advantage in the markets for workgroup server OSs and media player software. It ordered Microsoft to pay a €497m (£340m) fine, to offer a version of its Windows XP desktop OS without a built-in media player, and to document the communications protocols used by Windows workgroup server products so that others could build competing products.

Numerous deadlines for the supply of the documentation have come and gone. The EC initially gave Microsoft 120 days to provide the information, and threatened further fines in March and June last year. On 10 November the EC told Microsoft it would face fines of up to €2m (£1.4m) a day if it did not comply by 15 December, and finally imposed the €280.5m fine on 12 July.

Microsoft representatives in Europe could not immediately be reached for comment.