Google made the announcement during a visit of the Belgian Prime Minister, Elio Di Rupo (Francophone socialist). Google's data centre in Dour is one of the three largest operated by the company in the continent of Europe.
The 300 million will finance a major three-year expansion programme. Google hardware operations manager Freddy Bonhomme told the Belgian press agency Belga: "Work has just started. Between 300 and 350 people are being hired."
Employment levels may fall after the project is completed.