(Reuters) -President Donald Trump and Federal Reserve Chairman Jerome Powell sparred face to face Thursday over the cost of renovations of the central bank's Washington headquarters, with the Fed leader saying the president was wrong about the cost of the overhaul.

Trump, standing shoulder to shoulder with Powell as both wore construction helmets, said Fed renovation costs had jumped from $2.7 billion to $3.1 billion, causing the Fed chief to say "I'm not aware of that."

Trump replied, "It just came out" and Powell again questioned where the president's number had come from, as it had not come from the central bank.

Powell then noted that it appeared that the president had included in the current cost of fixing up two buildings what it cost to overhaul another central bank office. "You just added in a third building" that "was built five years ago. We finished Martin five years ago," the Fed leader said.

In the appearance, Trump was asked what he'd do to a project manager that had faced cost overruns of the sort faced by the Fed. "Generally speaking, what would I do? I'd fire him," the president said.

Powell also noted as he stood next to Trump that he didn't anticipate any more cost overruns but the Fed has reserves to deal with them if needed.