Inflation in the euro zone is proving tougher to crack than expected and the European Central Bank will likely need to raise interest rates further, possibly above 4%, Austrian central bank chief Robert Holzmann said on Saturday. "Inflation is proving much tougher than thought," Holzmann, a member of the ECB's policymaking Governing Council, told ORF 1 radio. "I do expect some more interest rate hikes," he said, adding that the extent of further increases would be data-dependent. Asked how high interest rates could go, after the ECB raised its benchmark refinancing rate to 3.50% on Thursday, he said: "Some of us ... (full story)