(BBC NEWS) - Microsoft has been fined 280.5m euros ($357m; Р€194m) by the European Commission for failing to comply with an anti-competition ruling.
The software giant was hit by the fine following a long-running dispute between the US firm and EU regulators.
The move follows a landmark EU ruling in 2004, which ordered Microsoft to provide rivals with information about its Windows operating system, reports Trend.
EU regulators also warned Microsoft it could face new fines of 3m euros a day.
The daily fines will come into force from 31 July if Microsoft fails to supply "complete and accurate" technical information to rival developers, the EU said.
Microsoft has insisted it is meeting the Commission's demands, and says it expects to deliver the final bundle of information for use by rival software firms by 18 July.
EU Competition Commissioner Neelie Kroes said she had "no alternative but to levy penalty payments" against Microsoft, adding that "no company is above the law".
"I regret that, more than two years after the decision... Microsoft has still not put an end to its illegal conduct," Ms Kroes said.
Brussels had warned Microsoft in December that it would face fines of 2m euros a day if the firm failed to meet the Commission's demands.
Under the 2004 ruling, Microsoft was told to provide rival firms with more information about its software, in order to enable them to write programs that could run more smoothly on Microsoft's widely-used Windows operating system.
The judgment also called for Microsoft to debundle its Windows Media Player from its Windows operating system, and slapped the software firm with a record fine of 497m euros.