China's electronics and information technology (IT) sector continued to expand in the first eight months of this year but companies faced growing pressure from higher costs and slower income, according to latest official data.

The value-added output of manufacturers in the sector rose 15.5 percent year-on-year in the January-August period and sales value increased 22.3 percent year-on-year, said the Ministry of Industry and Information Technology (MIIT).

During that period, exports of electronics and IT products climbed 15.5 percent year-on-year to $420.9 billion, said the MIIT.

Meanwhile, 21.8 percent of the sector's companies were in the red in the January-July period, with their combined losses surging 73.7 percent year-on-year, according to the MIIT.

The electronics and IT companies were facing increasing costs, said the ministry.

In July, the sector's revenues grew 18.3 percent year-on-year, down 5.5 percentage points from June, according to the statistics.