Row over Belgian football racism
Supporters of Genk chanted anti-Walloon abuse but faced no sanction.
Supporters of Genk in the Flemish-speaking north of the bilingual country made derogatory comments about their Walloon (Francophone) counterparts during a league match with Tubize from the south.
Tubize official Louis Derwa protested to the referee, who briefly halted the match. Afterwards, Derwa complained to the Federation but on Monday the authorities came back with the view that the chants "were not injurious but should be taken in a playful, mocking and teasing context."
Tubize and fellow southern side Standard Liege reacted with consternation, blasting the judgment of the authorities as "irresponsible" and one which "trivialises the insults" while "sending out a bad signal to young supporters and players."
Tuesday saw the row spread with the chief minister of the Wallonia region, Rudy Demotte, blasting the Federation for its "unacceptable" response which "shows a lack of respect and consideration for an entire region of the country."
Fellow francophone official Olivier Maingain said he was concerned about the fans' behaviour and called on the authorities to take a hard line. lamenting the Federation had not done so.
Both language groups are already at loggerheads over planned institutional reform.
Football racism and sectarianism has hit the headlines in several European countries in recent days.
On Sunday, French champions Lyon complained their Ghanaian defender John Mensah had been repeatedly showered with racial abuse during a win over Le Havre, one of whose fans was arrested.
Mensah grew increasingly and visibly upset and was ultimately sent off after picking up two yellow cards.
Tuesday, his lawyer said he remained deeply upset.
In Scotland, Sunday's draw between Glasgow rivals Rangers and Celtic saw an outbreak of sectarian chanting by a section of the Rangers fans and a report has been submitted to the Scottish Premier League (SPL) authorities, BBC Scotland said on Tuesday.
Last October the SPL said it would act to curb renditions by some Rangers fans of a song which alludes to the great Irish potato famine in the 1840s and which led to a mass migration from Ireland.
Predominantly Catholic Celtic have many fans in the Republic of Ireland.