Sales by China's major excavator producers continued to expand fast in May, adding to evidence that economic activity remains strong.

The country's 25 leading excavator makers sold 19,313 digging machines in May, up 71.3 percent year-on-year, according to the China Construction Machinery Association.

More than 17,700 machines were sold in the domestic market, up 69.6 percent year on year. Overseas sales surged 95.3 percent to over 1,500 machines.

A total of 105,935 excavators were sold in the January-May period, up 60.2 percent from a year earlier.

Sales of digging machines are an indicator of the vitality of an economy as demand is usually backed by growth in mining and infrastructure development.

China's manufacturing sector grew at the fastest pace in eight months in May, with the purchasing managers' index standing at 51.9 in May, up from 51.4 in April, according to the National Bureau of Statistics.