A top policymaker at the U.S. central bank decried the “accelerationist approach to monetary policy” among some of his colleagues, pointing to signs of economic improvement as reason enough for the Federal Reserve to stand pat for now.

Philadelphia Fed President Charles Plosser on Tuesday stepped up his long-standing opposition to the Fed’s ultra-easy policies, warning that any further steps to spur the U.S. recovery would be “treacherous” and risk sparking inflation down the road.

Read more: Fed’s Plosser: More Easing Would Put US on ‘Treacherous Path,’ Spark Inflation