BEIJING - China's major industrial firms posted double-digit growth in profits in the first five months of this year, adding to signs of a stabilizing Chinese economy, official data showed Tuesday.

Industrial companies with annual revenue of more than 20 million yuan (about $2.93 million) reported profits of 2.9 trillion yuan in the first five months, a 22.7-percent increase from one year earlier, the National Bureau of Statistics (NBS) said in a statement.

The profit growth was down from 24.4 percent in the first four months but much faster than the 8.5-percent increase in 2016.

In May alone, profits of major industrial firms rose 16.7 percent year on year, up from 14 percent in April, the NBS said.

The faster growth in May was partly boosted by stronger sales and increased return on investments by companies, said He Ping, a NBS statistician.

The finished goods inventory of major industrial firms rose 9.3 percent by the end of May, 1.1 percentage points slower than a month ago, the first time that growth pace has moderated this year.

Industrial profits have maintained an upward trend, with improved structure and rising profitability reported by many firms, said He.

Among all the profits made by major industrial firms in May, those from the mining industry accounted for 35.5 percent, a drop of 18 percentage points compared with a month ago.

Equipment manufacturing took a bigger share of the profits compared with April while consumer-goods manufacturing also saw faster growth, indicating better structure, according to He.

Companies also reported healthier balance sheets. The average collection period for accounts receivables decreased from 39.1 days a year earlier to 38 days by the end of May, continuing a downward trend from the beginning of this year.

Leverage ratio kept declining, with debt-asset ratio of major industrial firms dropping 0.7 percentage points year on year to 56.1 percent by the end of May.

Still, He warned against rising costs for major industrial firms, noting that the cost per 100 yuan of revenue made from primary businesses edged up year on year for the third consecutive month in May.

The industrial sector, which accounts for about a third of China's GDP, started to pick up last year after profit declines in 2015, helped by government efforts to cut overcapacity and a recovery of the property sector.