BEIJING — China's rail-cargo volume, a key indicator of economic activity, rose 6.6 percent year-on-year to a record high in May, as the country further smooths logistics to underpin the economy amid COVID-19 control, according to data issued by the China State Railway Group on June 1.

A total of 340 million tons of cargo was transported on China's railways in the period, 21.1 million tons more than that in the same period last year, according to the company.

Among the cargo was 5.02 million tons of grain and fertilizers, a 28.2-percent increase year-on-year, the data shows.

The country also ferried 110 million tons of coal used for power generation via railways last month, up 7 percent year-on-year, ensuring coal storage in 363 power supply plants for 33.4 days.

Last month, China-Europe freight trains handled 129,500 twenty-foot equivalent unit containers, with the average daily volume climbing 13.3 percent from April. The China-Laos Railway saw 138,200 tons of goods transferred for cross-border trade, up 4.3 percent from a month ago.