SEOUL (AFP) - North Korea on Monday (July 11) threatened to take "physical action" to counter a sophisticated US anti-missile system planned to be deployed in the South.

"The DPRK will take a physical counter-action to thoroughly control Thaad... from the moment its location and place have been confirmed in South Korea," the artillery bureau of the North's military said in a statement, according to the official Korean Central News Agency (KCNA).

North Korea's military, which has "sufficient latest offensive strike means", will take "more merciless and powerful successive corresponding measures against the US keen to ignite a war by deploying Thaad", it said.

It also warned the South of "miserable self-destruction" as a consequence of the introduction of the Terminal High Altitude Area Defence (Thaad) system.

The United States and South Korea on Friday said they would deploy the missile defence system in the South but the time and venue are yet to be fixed.

Chinese Foreign Minister Wang Yi said on Saturday that Thaad exceeded the security needs of the Korean peninsula, and suggested there was a "conspiracy behind this move."

South Korean Finance Minister Yoo Il Ho downplayed the possibility that China, Seoul's biggest trading partner, would retaliate economically over the Thaad decision.

"(China) is expected to separate politics and economics," he told lawmakers on Monday in response to a question during a parliamentary session.

A South Korean Defence Ministry official said selection of a site for Thaad could come "within weeks," and the allies were working to have it operational by the end of 2017.

It will be used by US Forces Korea "to protect alliance military forces," the South and the United States said on Friday.

The United States maintains 28,500 troops in South Korea, a legacy of the 1950-53 Korean war. The system will be focused solely on North Korean nuclear and missile threats and would not be directed towards any other nation, the two countries said last week.