BEIJING - The volume of rail freight dropped during the January-March period as economic activities showed no signs of improving, official data showed on Monday.

Railways transported 870 million tons of cargo in the first quarter of the year, down 9 percent year on year, according to China Railway Corp.

This data adds to a slew of other economic indicators that show prolonged weakness in the economy.

Dragged down by a housing slowdown, softening domestic demand and unsteady exports, the economy grew 7.4 percent in 2014, its weakest annual expansion in 24 years.

Chinese Academy of Social Sciences estimates gross domestic product (GDP) growth in the first quarter will slow to about 6.85 percent.