BEIJING -- China's top 500 private enterprises saw steady growth in their ability to innovate during 2019, according to a report released by the All-China Federation of Industry and Commerce (ACFIC).

Within the leading 500 firms, the key technologies of 402 companies were mainly developed independently, accounting for 80.4 percent of the total, says the 2020 survey and analysis report on China's top 500, which is based on 2019 data.

The number of valid patents obtained by the top 500 increased by 8.46 percent in 2019, while the figure for international patents also grew significantly, according to the report.

The enhanced innovation capability was fueled by hefty research and development (R&D) investment. According to the report, the biggest spender on R&D spent 131.6 billion yuan (about $19.2 billion) in 2019, with the second biggest spending 20.7 billion yuan.

The report also highlights figures for R&D intensity, the proportion of R&D expenditure to main business revenue. Among the top 500 private companies, 59 had an R&D intensity of more than 3 percent in 2019, while five companies surpassed 10 percent.

In 2019, the top 500 private enterprises accelerated their transformation and upgrading, enhanced their innovation capability and sharpened their core competitiveness, said Huang Rong, vice chairman of the ACFIC.

Meanwhile, they made efforts to forestall and defuse major risks, carry out targeted poverty alleviation, prevent and control pollution, as well as play an active role in implementing major national strategies and the coordinated regional development strategy, Huang added.

Among the leading 500 firms, 403 engaged in fighting pollution, 355 in targeted poverty relief, 291 in rural vitalization and 191 in the Belt and Road construction, according to the report.