The rift has widened with television reports this week that mayors in Flemish districts around the capital are giving preference in the sale of publicly-developed housing stock to Flemish buyers, in an effort to maintain their "Flemish character."

Verbal deals with developers or real estate agents ensure municipal authorities are able to vet interested buyers first.

The practice is said to go back years, and would run counter to the publicly-held position in French-speaking communes or the officially bilingual capital city.

"We have received two complaints based on fundamental liberties in European Union treaties and in particular relating to the purchase of private property," said a European Commission spokeswoman.

Chantal Hugues told a daily press conference that the EU's legal guardian was taking the complaints "seriously," less than three months from Belgium assuming the revolving chair of the bloc.

The EU guarantees its half a billion citizens the right to free movement across the 27 member countries but regularly receives complaints linked to policies in Flemish areas on the doorstep of its capital Brussels.

AFP/Expatica