US economic activity continued to expand from mid-February through the end of March, but a strong dollar and falling oil prices were hurting the manufacturing sector, the Federal Reserve has said.

In its Beige Book report of anecdotal information on business activity collected from contacts nationwide, the central bank said most of its regional Fed banks described growth as either progressing at a "moderate" or "modest" pace.

"Demand for manufactured products was mixed during the current reporting period. Weakening activity was attributed in part to the strong dollar, falling oil prices, and the harsh winter weather," the Fed said.

The report, compiled by the Cleveland Federal Reserve Bank with information collected on or before 3 April, provided a look at some of the trends in manufacturing and residential construction that have already appeared in other data. 

It said there was a decline in oil and gas drilling investment and noted that related job losses were reported in multiple districts.