Democratic People's Republic of Korea(DPRK) appears to be preparing for a long-range missile test, South Korea's Yonhap News Agency reported on Saturday, citing an informed source.

The source, asking not to be identified, said an intercontinental ballistic missile (ICBM) was recently spotted on a cargo train near Pyongyang, Yonhap said.

The missile has since been moved to an undisclosed location, according to the source.

"It usually takes about two months to set up a launch pad, but the process could be done in as little as two weeks, which means the North could launch a long-range missile as early as in mid-June," the source said.

The remarks came shortly after a defense source said some activities were spotted at a DPRK's munitions factory used to build long-range missiles.