BEIJING, Jan. 7 (Xinhua) -- China's container transport for export purposes lost steam in December over lackluster demand on some routes, according to data from the Shanghai Shipping Exchange.

The average China Export Containerized Freight Index stood at 849.69 points in December, down 0.5 percent from a month earlier, the exchange said in a statement.

Last year, the index averaged 817.8, slightly lower than an average of 820.47 points for 2017.

In December, the sub-index for the Persian Gulf/Red Sea route saw the strongest rally of 9.1 percent, while that for the Korean and Southeast Asian routes nudged up 2.5 percent and 1.2 percent, respectively.

The sub-index for South American route dropped the most by 11.9 percent, the data showed.

The China Export Containerized Freight Index was first released by the Shanghai Shipping Exchange in April 1998 as a barometer for the export shipping market.