OTTAWA (CP) -- Manufacturers gave back some of their recent gains in March as factory sales retreated 1.6 percent to $49 billion, their first decline of 2008.

The scope of March's slowdown was extensive as 18 of the 21 manufacturing industries, representing 76 percent of total sales, posted declines.

A sharp downturn in motor vehicle sales was the chief contributor.

Manufacturing sales fell 5.5 percent to $143.8 billion in the first quarter of 2008, compared with the same period last year.

Statistics Canada in part blamed market uncertainty in the United States, Canada's dominant trading partner, for the volatility in some manufacturing industries.

Ontario, down 2.9 percent, and Alberta, down 1.4, led declines among the six provinces reporting lower sales in March, while Quebec sales rose 0.3 percent on the strength of the aerospace industry.

The agency says that, in terms of the volume of goods manufactured, rising industrial prices for various commodities, including primary metals, petroleum products, grains and oilseeds, may be partly offsetting some of the weakness in the manufacturing sector.