The Punggye-ri nuclear test site in North Korea is seen in this May 14, 2018, satellite photo. / Korea Times file

The South Korean military is not ruling out the possibility of North Korea conducting a nuclear test in a "short period of time," an official here said Monday.

The defense official's remarks came amid concerns the North could conduct what would be its seventh nuclear test around the time when South Korean President Yoon Suk-yeol and his U.S. counterpart, Joe Biden, meet in Seoul for a summit set for Saturday, or shortly afterward.

"Our military is bracing for the worst-case scenario of the North conducing a nuclear test in a short period of time, and it is maintaining a firm readiness posture," the official told reporters on condition of anonymity.

The military authorities here believe that the reclusive regime has made "considerable" preparations for a nuclear test at its Punggye-ri nuclear test site, a source said, noting they have detected signs of such preparations since March.

Uncertainty remains over the timing of the nuclear test, observers said, as Pyongyang has been struggling to contain COVID-19 outbreaks with a "maximum emergency" virus control system in place.

Some others, however, presume that the North could press ahead with a nuclear test based on its own timetable for a project to master the technology to make nuclear warheads smaller and lighter.

Last Friday, an official at South Korea's presidential office said that the North appears "ready" for a nuclear test, and that prior to this, it could launch multiple kinds of missiles. (Yonhap)