U.S. export prices rose 1.5 percent during the month, also more than expected and the largest monthly gain on record, as prices for farm and food products continued to rise. (Video: Analysis of March import prices)

Analysts polled by Reuters had forecast a 2 percent rise in import prices in March after a 0.2 percent gain in February. They also forecast a 0.5 percent rise in export prices after a previously reported 0.9 percent gain in February, which the Labor Department revised to 1.1 percent.

The larger-than-expected rise in import prices boosted the dollar in early trading after the report. Stronger inflation could limit the Federal Reserve's ability to cut interest rates during the current economic slowdown.

Import prices have risen 14.8 percent over the last 12 months, the largest year-to-year gain since the Labor Department began publishing the data.

A large factor was petroleum prices, which have risen 60 percent over the past year, although prices for food, feed and beverages have increased 14 percent.

Export prices have risen 7.9 percent over the last 12 months, the largest increase since the Labor Department began publishing the data.

Prices for agricultural exports and food, feed and beverage exports have both risen more than 33 percent over the past year.