Toll road policies need to be improved, but the debt remains manageable, said Wang Tai, deputy director of China's Ministry of Transportation.

By the end of last year, the construction debt balance had decreased from 4.27 trillion yuan ($688 billion) of total accumulated debt to 3.85 trillion yuan, which means nearly 10 percent of the debt has been paid off, according to a statistical bulletin on road toll fees released by the ministry on Tuesday.

A total of 263.7 billion yuan, out of 391.6 billion yuan collected in toll fees last year, went to principal and interest payments related to construction, with the rest covering road maintenance, taxes and overhead, the report said.

The amount repaid exceeded what was required, Wang said.

"Heavy debt has to do with rising costs and the road construction binge since 2010, which saw the addition of more than 30 percent to highway miles," Wang said. "The policy now needs to be improved to ease the debt burden."

By last year, China had 162,600 kilometers of toll roads, accounting for 3.6 percent of the national road system.