China has instructed travel agencies in the country to stop selling trips to South Korea, sources said Thursday, in what is seen as another retaliatory move against Seoul's decision to deploy an advanced US anti-missile defense system. 

According to industry sources in China, the China National Tourism Administration (CNTA) called travel agencies in Beijing for a meeting on Thursday and gave them verbal instructions to suspend sales of all travel packages, both online and offline, to South Korea. 

It means that any package tours or free trips sold by travel agencies will not be available to Chinese wishing to visit Korea. 

While ordering to immediately put a halt on all trip sales, the agency told them to exhaust those that have already been sold by mid-March, sources said.

Such a measure will likely be imposed on the travel agencies based in other cities nationwide following regional meetings that will be held soon, they added.

The move by the Chinese authorities is the latest in a series of what are viewed as retaliatory acts against the planned deployment of a high-tech U.S. anti-missile defense system in Seoul, known as Terminal High Altitude Area Defense (THAAD).