Europe’s new antitrust chief has warned that telecoms mergers must not endanger “affordable prices” for consumers, in a shot across the bows of dealmaking executives that suggests takeovers will face tougher EU scrutiny.

Margrethe Vestager — who vets all big EU mergers and oversees sensitive investigations ranging from US tech group Google’s alleged abuse of its dominant position to sweetheart tax deals for multinationals — wields far-reaching powers to impose hefty fines or block takeovers without court approval.

With a wave of proposed mergers reshaping markets from Britain to Denmark, Ms Vestager has stressed the need to avoid price increases in her most detailed comments on the telecoms sector since becoming EU competition commissioner. “I have one interest and that is to make sure that European consumers — that being citizens or businesses — can enjoy relatively innovative markets at affordable prices,” she said in a Financial Times interview.