South Korea lashed out Monday at an "unspeakable" personal attack on its president, a day after Pyongyang called Park Geun-Hye a "prostitute".
In a vicious statement released through state media, North Korea likened Park Geun-Hye to a "comfort woman" and accused her of pandering to her "pimp" Barack Obama. The word used can also mean "sugar daddy".
The vitriol came after the US president, who visited South Korea last week as part of an Asian tour, joined Park to urge the North to abandon its nuclear ambitions and warned it against staging another atomic test.
The North's Committee for the Peaceful Reunification of Korea accused Park of being Obama's "puppet" in their bid to further isolate Pyongyang.
"She... laid bare her despicable true colours as... a dirty comfort woman for the US and despicable prostitute selling off the nation," it said.
The astonishing invective follows months of increasingly colourful personal attacks on Park, in which the North has likened her to a "peasant woman babbling to herself" and said she is a "low-quality politician" who talks "nonsense gibberish."
Seoul hit back on Monday at the latest "immoral" utterances and urged Pyongyang to honour an agreement reached in February in which both sides said they would lay off the verbal fisticuffs.
"The North... not only broke the agreement once again but also continued to issue unspeakable curses and foul words in an immoral act," said Kim Eui-Do, spokesman for the unification ministry, which handles cross-border affairs.
"If the North has the slightest feeling for its own people... it should stop its senseless behaviour and take the path to cooperation and joint prosperity," he said.
Vituperative outbursts from the isolated regime are nothing new, and Park's predecessor Lee Myung-Bak was rarely referred to without having an unflattering adjective attached to his name.
But attacks on Park -- South Korea's first female president -- have frequently taken a highly misogynistic tone.
Tension on the Korean peninsula is running high after satellite imagery showed there was increased activity at the North's nuclear test site, signalling potential preparations for another atomic test.
The impoverished but nuclear-armed North has staged three nuclear tests, in 2006, 2009 and 2013 at the Punggye-ri test site in the country's northeast.