North Korea threatened Wednesday to wage a retaliatory war against President Park Geun-hye in the latest show of defiance against tougher U.N. sanctions and joint military drills between Seoul and Washington.

North Korea vowed to "launch a retaliatory battle of justice to resolutely eliminate" the United States and Park, warning that it is ready to turn South Korea's presidential office into a sea of fire.

"The powerful large-caliber multiple rocket launching systems of invincible Korean People's Army artillery units are highly alerted to scorch Cheong Wa Dae... in a jiffy," the North's committee handling inter-Korean affairs said in a statement carried by the country's official Korean Central News Agency.

It warned that once buttons are pushed, the South's presidential office "is bound to be reduced to a sea in flames and ashes."

North Korea has made similar threats in the past, but the latest one came amid growing speculation that it may carry out another nuclear test and launch missiles in the near term.

The North conducted nuclear tests in 2006, 2009 and 2013, followed by a fourth in January.

Seoul and Washington have started their largest joint military drills ever, which will come to a close on April 30. The North has long denounced them as a rehearsal for a northward invasion, a charge denied by Seoul and Washington.

The North ratchets up its bellicose rhetoric whenever Seoul and Washington hold the military exercises.

South Korea vehemently condemned the North for warning of attacks on Park, calling for an immediate end to such "vulgar" acts.

"We will never condone the North's threats against President Park and our people," Jeong Joon-hee, a spokesman at the Unification Ministry, told a regular press briefing. "North Korea should immediately end its vulgar and despicable acts."

He added that South Korea's military will "sternly and relentlessly" respond to any additional provocation by the North.

The North has made numerous threats following the United Nations Security Council's latest sanctions over Pyongyang's January nuclear test and long-range rocket launch in February.

North Korea last week launched two medium-range ballistic missiles, with one believed to have blown up in mid-flight. It also fired several short-range projectiles this month into waters off its east coast.

The North also said it plans to conduct nuclear warheads and ballistic missiles tests "in a short time," raising speculation over its additional provocations.

Experts say that Pyongyang may see somewhere between the end of the military drills and its party event slated for early May as a prime time for high-profile provocations, including sporadic military actions.

South Korea's spy agency said that the North is likely to hold its ruling party congress on May 7, the first in more than three decades.

"The North appears to aim to show its strong protest against the Seoul-Washington drills and raise tension for higher internal solidarity," said Yang Moo-jin, a professor at the University of North Korean Studies. (Yonhap)