PYONGYANG - The Democratic Peoples Republic of Korea (DPRK) on Monday denounced US-South Korea joint drills as severe provocation, and vowed to bolster its nuclear deterrence for self-defense.

A spokesman for the DPRK Foreign Ministry issued a statement slamming the largest ever US-South Korea joint drill on Friday in the area south of the Demilitarized Zone, which even perpetrated firing at the DPRK flag, according to the official KCNA news agency.

"It is an extremely grave military action and politically- motivated provocation to fire live bullets and shells at the flag of a sovereign state without a declaration of war, the statement said.

The drill once again proved that the commitment which the US made in the February 29 DPRK-US Agreement that they would not antagonize the DPRK was a sheer lie, whose recent hostile policy towards the DPRK has gone beyond the tolerable limit, it said.

The spokesman said that the DPRK will further bolster up its nuclear deterrent for self-defense as long as the US persists in its hostile policy towards it.

On Friday, South Korea and the United States staged their largest ever live-fire drill northeast of Seoul, aimed at checking solid military preparedness and war-fighting capabilities, according to the South Koreas Defense Ministry. ?

A spokesman for the National Peace Committee of Korea denounced the joint military exercises as an intentional act to provoke war, which has pushed the Korean Peninsula and the rest of Northeast Asia to the edge of armed conflict

US President Barack Obama ?last Monday decided to extend for one year the sanctions against the DPRK, citing the "unusual and extraordinary threat" posed by the Asian country to US national security, foreign policy and economy.