The Federal Reserve Bank of Cleveland Loretta Mester said in a speech on Friday that the Fed could start raising its interest rate if the incoming economic data will be positive.

"If incoming economic information continues to support this forecast, then in my view it will be time to take the first step in the policy normalization process," she said.

Mester also said that U.S. labour market continues to improve and inflation is gradually returning to the Fed's 2% target over the medium period.