U.S. economy expanded moderately in late April and early May, with the manufacturing shifting into higher gear, according to a Federal Reserve survey released on Wednesday.

More than half of the Fed's 12 regional districts reported "a pickup" in manufacturing activity and a third of the districts classified activity as "strong," said the Fed in its latest survey on economic conditions, known as the Beige Book, based on information collected through May 21.

"Fabricated metals, heavy industrial machinery, and electronics equipment were noted as areas of strength," the survey said, adding rising goods production led to higher freight volumes for transportation firms.

While U.S. businesses noted some concern about the uncertainty of international trade policy, the outlooks for near term economic growth were "generally upbeat," the survey showed.

Analysts said Wednesday's report is likely to pave the way for the Fed to raise interest rates again at its next policy meeting scheduled on June 12-13.

The central bank has signaled that it will raise interest rates "soon" if economic outlook is in line with expectation of Fed officials.

"Most participants judged that if incoming information broadly confirmed their current economic outlook, it would likely soon be appropriate for the (Federal Open Market) Committee to take another step in removing policy accommodation," the Fed said in the minutes for its latest policy meeting released last week.