"We do not have a statement or anything to provide on that," the spokesperson said when asked about the reports.
On Monday, the Washington Post reported that US intelligence agencies have seen signs of construction of new missiles in North Korea.
Citing officials familiar with the intelligence, the report said that satellite photos and other evidence show that work is underway on at least one or possibly two liquid-fueled ICBMs at a research facility in Sanumdong.
North Korea made rapid improvement in nuclear research last year, managing its strongest atomic test to date and testing a series of missiles.
On June 12, North Korean leader Kim Jong-un met with US President Donald Trump in Singapore, where the two leaders agreed on Pyongyang's denuclearization in exchange for a freeze of the US-South Korean military drills and eventual sanctions relief.