The Schalke chairman, Clemens Tönnies, is under pressure to resign following widespread condemnation of racist comments he made last week.

Speaking at a public meeting with 1,600 guests in Paderborn, the 63-year-old criticised tax increases designed to help to fight climate change and then suggested the money would be better used financing 20 power plants a year in Africa.

“Then the Africans would stop cutting down trees, and they would stop making babies when it gets dark,” Tönnies has been quoted as saying – a statement which later prompted an apology.

“I am for an open and diverse society,” he said. “I am sorry for the comment on the large number of children in Africa. As chairman of the supervisory board of FC Schalke 04, I am 1,000% behind our club values. This includes the fight against racism, discrimination and exclusion. On the basis of that I expressly wish to excuse myself. It was wrong, rash and thoughtless and in no way in line with our values. I am very sorry.”

Yet despite the apology by Tönnies the German justice minister, Christine Lambrecht, has called for the German Football Association (DFB) to intervene.

“Racism must be loudly and clearly contradicted at every opportunity,” she said. “Nowhere is integration as successful and quick to work as in sport – that must not be put at risk.”

Dagmar Freitag, chairman of the sports committee in the German parliament, told the newspaper Welt on Sunday: “The fact that something like this is articulated by someone who holds a prominent position in sport makes things all the worse.”

Nikolaus Schneider has confirmed that the case will be discussed at the next meeting of the DFB ethics committee on 15 August.

The son of a butcher who founded a meat-processing company that is now one of the biggest in Europe, Tönnies has been Schalke’s chairman since 2001 and is worth an estimated £1bn. David Wagner’s side begin their Bundesliga season on 17 August against Borussia Mönchengladbach.