South Korea and the United States are closely watching North Korea for any signs for a possible imminent provocation, the foreign ministry in Seoul said Thursday, amid concerns that Pyongyang is preparing a missile test-fire that runs counter to global sanctions.

"Military authorities of South Korea and the US are closely monitoring any signs of the North's ballistic missile test," Cho June-hyuck, a ministry spokesman, said at a regular press briefing. 

"The North should come out to the negotiating table knowing that any provocation could result in much tougher sanctions and pressure," he added. 

Citing US government sources, CNN earlier reported that there are signs that North Korea is preparing to test an intercontinental ballistic missile or intermediate range missile within two weeks.

The North test-fired what it claimed was an ICBM on July 4 in defiance of multiple UN Security Council resolutions that ban its use of any ballistic missile technology. The UNSC is working on additional sanctions to punish the North's latest provocation. (Yonhap)