KKR, a New York-based private equity firm with $126 billion of assets, said it won’t make an acquisition of a British company before the country votes on whether to leave the European Union because of uncertainty about the outcome.

Exiting would be "dire" for the British economy, Johannes Huth, the European head of the firm, said in an interview at his London office. His case for staying in the EU is one of the strongest made so far by a business leader. If Britons vote to leave on June 23, KKR would respond by moving some of its London operations to Dublin, Paris, Madrid or Luxembourg to maintain the firm's ability to sell its funds to investors across the region, he said.