The nation's top planning authority pledged on Friday to boost private sector investment, which is key for the economy while growth is on the wane.

"The government will further relax market access and simplify approval procedures to encourage more private firms to make investments," said Xu Kunlin, head of the National Development and Reform Commission's fixed investment department.

Xu made the comments after Zhao Chenxin, NDRC spokesman, said on Thursday that the government would offer more support for private firms to help them broaden finance channels.

Zhao stressed that the government would further plays its leading role in guiding investment in key projects.

A total of 13 new fixed asset investment projects worth 138.8 billion yuan ($21.3 billion) have been approved by the commission this month, including waterworks construction, transport and energy projects, according to Zhao.

The State Council said in a meeting earlier this month that private investment was important for the economy, adjusting economic structures and promoting employment, but had slowed recently.

Official data showed fixed-asset investment by private firms rose 5.7 percent in the first quarter from a year earlier, slowing from a 10.1 percent rise in 2015.