Blackstone sought approval from the European Commission on June 15, according to the filing on the website.

The Commission can either clear the deal with or without concessions or it can open a full-scale investigation of about four months if it has serious concerns.

Thomson Reuters' Financial & Risk business, which provides news and analytics to financial services companies, competes with Bloomberg and News Corp Dow Jones unit.

(Reporting by Foo Yun Chee. Editing by Jane Merriman)