North Korea slammed former US Vice President Joe Biden for denouncing the communist regime and called him a “rabid dog” that should be “beaten to death”, according to the state media on Friday.

The attack came two weeks after Biden issued a statement attacking President Donald Trump’s North Korea policy and referring to that country’s leader, Kim Jong Un, as a “murderous dictator.”

In response to Biden, North Korea laid on the animal metaphors thick and fast, calling Biden a crafty, rabid dog keen at getting at others’ throats, and a profiteer.

“A crow is never whiter for often washing,” the Korean Central News Agency said in a commentary.

Pyongyang is renowned for its vitriol, but the verbal deluge was unusually ferocious even by its own standards.

Biden, a leading Democratic presidential candidate, has been vocal about his criticism of US President Donald Trump’s approach to North Korea in negotiations to denuclearize the regime.

The criticism of Biden came just a day after North Korea issued a rare criticism of Trump, and could be seen as an attempt to leave a small window open for dialogue with the current administration.

On Thursday, North Korea rejected US offer for fresh talks and said that it was not interested in more talks merely aimed at “appeasing us” ahead of a year-end deadline Pyongyang has set for Washington to show more flexibility in negotiations.

The negotiations have faltered since a February summit between Kim Jong Un and President Donald Trump in Vietnam collapsed after the US side rejected North Korean demands for broad sanctions relief in exchange for a partial surrender of its nuclear capabilities.

In July, he accused Trump of embracing “thugs” like North Korean leader Kim Jong-un and giving him the legitimacy he craves on the world stage.

Earlier on Friday, KCNA described Biden as a “profiteer” who is greedy for power and “wandering about like a starving field dog”.

In May, Pyongyang issued similar angry remarks at Biden and called him a “fool of low IQ” after he called leader Kim a “dictator and tyrant” during a campaign speech.