Growth in the U.S. manufacturing sector dipped more than expected in April, with factory activity showing the slowest momentum since January, according to an industry report released Thursday.

Financial data firm Markit said its preliminary U.S. Manufacturing Purchasing Managers' Index fell to 54.2 in April from the final March read of 55.7. Economists polled by Reuters had forecast the April figure would come in at 55.5.

A reading above 50 indicates growth in the sector.

"While growth has clearly slowed in 2015 compared to the impressive rate seen throughout much of last year, the goods-producing sector is by no means collapsing under the weight of the strong dollar, and fears of a sharp slowdown consequently look overplayed," said Chris Williamson, Markit's chief economist.

The index's flash output component fell from the final March read of 58.8 to 55.4, which was also the weakest since January.

The flash reading of the index measuring new orders also weakened in April, coming in at 55.4, compared with March's reading of 57.2.

Employment growth also weakened in April from March, Markit said, though the drop was more modest.