Jean-Claude Juncker hit back at German and French critics of European Union competition policy as his top antitrust official prepares to veto a high-profile rail merger between Siemens AG and Alstom SA.

The president of the European Commission, the EU’s executive arm, said its antitrust approach lets strong companies emerge in Europe. In the almost 30 years since the first European merger rules were put in place, the commission has approved more than 6,000 deals and blocked fewer than 30, he said.

“This is a message for those who are saying that the commission is composed of blind, stupid, stubborn technocrats,” Juncker told a conference on Tuesday in Brussels. “We believe in competition as long as it is fair for all. We’ll never play politics or play favorites when it comes to ensuring a level playing field.”

The comments symbolize how politically charged the commission’s scrutiny of the Siemens-Alstom deal has been in recent months. Public rumblings of any kind are unusual in such vetting procedures, with the commission’s antitrust officials usually operating out of the spotlight and free of political meddling.

EU Competition Commissioner Margrethe Vestager may rule as soon as Wednesday on the Siemens-Alstom tie-up, which is meant to create a European champion able to compete with an expansive Chinese competitor.

“We will always allow competition that is fair for business and ultimately fair for the consumer,” Juncker said on Tuesday.