The Democratic People's Republic of Korea (DPRK) has denounced the warning shots fired at its fishing boats by South Korean warships along their disputed western sea border as acts of provocation.

A report from the official KCNA news agency said on Saturday that South Korea's actions were "nothing but an adventurous military provocation."

KCNA also quoted the Southwest Front Command of the Korean People's Army (KPA) as saying that the command was ordered to stand ready to fight a "great war of national unification" if the south fires "even a bullet" into its territory.

South Korea's Navy on Friday fired warning shots at six DPRK's fishing boats, which crossed a disputed western border called the Northern Limit Line (NLL), and retreated.

The DPRK refuses to acknowledge the NLL, which was drawn unilaterally by the U.S.-led UN Command at the end of the 1950-53 Korean War.

The South Korean Navy has reportedly raised the alert level along its western sea border in response.

The disputed demarcation line has long been a crucial element that would trigger tensions between the two sides.

The DPRK and the South Korea exchanged fires in the disputed waters in November 2010, killing at least two South Korean marines and injuring 16 others.