BEIJING - China's cement output grew 5 percent from a year earlier to 793.98 million tons in the first five months, the country's top economic planner said Saturday.

The growth rate, however, represented a sharp decrease of 14.3 percentage points from the same period of last year, data with the National Development and Research Commission showed.

In May, cement output increased 4.3 percent year-on-year, down from 19.2 percent recorded last year.

The sharp decrease came as economic slumps both at home and abroad have dampened market demands. The building material sector has been particularly weighed down due to the government keeping real estate controls in place.

Meanwhile, flat glass output dropped 1.7 percent year-on-year to 298.28 million weigh boxes in the first five months, in comparison to an increase of 19.6 percent last year.

In May, flat glass output dropped 10.2 percent, compared to 21.7-percent growth last year.

Over the January-April period, the building material sector saw profits drop 7 percent from a year earlier to 81.3 billion yuan ($12.9 billion).

In the period, profits of cement producers dropped 59.9 percent to 9.53 billion yuan, while the flat glass sector recorded losses of 130 million yuan, compared with 2.35 billion yuan in profits during the same period last year.