GUANGZHOU, March 9 (Xinhua) -- A new metro line linking Shenzhen airport with the city's downtown is scheduled to start operating in June, Shenzhen Metro said on Wednesday.

Workers are now testing signals on the 52-kilometer line, the company said.

The metro line will have 18 stations.

The line is designated as an airport express line serving one of China's biggest cities and a hub for hi-tech industries.

Trains on the line can run up to 120 kilometers per hour, the company said.