WASHINGTON (REUTERS) - The United States said on Tuesday it was closely monitoring the situation on the Korean peninsula following reports that North Korea may be planning another nuclear test and it urged Pyongyang not to take any step that would threaten regional peace.

"We have certainly seen the press reports ... regarding possible increased activity in North Korea's nuclear test site,"US State Department spokesman Jen Psaki told a regular briefing.

"We are closely monitoring the situation on the Korean peninsula." "We continue to urge North Korea to refrain from actions that threaten regional peace and security and to comply with its international obligations and commitments."