North Korea has reportedly ordered its frontline troops to be put on "special alert," raising speculations that Pyongyang is preparing to engage in provocations sometime around the ruling party congress set for Friday.

A government source in Seoul said on Tuesday that the North recently issued the order, adding that the South Korean military is closely monitoring the movements of the North Korean troops amid the possibility that the North may attempt to launch a provocation around the time of its ruling Workers' Party congress.

The South Korean military is said to be enhancing its monitoring of land, sea and air in the area of the Military Demarcation Line(MDL) using surveillance assets of Seoul and Washington.

North Korea is reportedly controlling operations of fishing boats at specific areas of the East Sea and Yellow Sea, prompting speculation that the North will fire a short or medium-range missile around the party congress.