North Korea's state media has accused former US vice president Joe Biden of slandering its leader and called the Democratic presidential candidate “a rabid dog” that needed to be put down.

The official KCNA news agency did not say how Mr Biden had insulted Kim Jong-un, but the 2020 presidential hopeful has been critical of Donald Trump's policy towards the secretive communist state, saying he was coddling a murderous dictator.

Misspelling Mr Biden's name, KCNA said the former vice president was showing signs of “the final stage of dementia”, and the “time has come for him to depart his life”.

In a commentary, it said, “Such a guy had the temerity to dare slander the dignity of the supreme leadership of the DPRK,” using the North's official name, the Democratic People's Republic of Korea.

“It was the last-ditch efforts of the rabid dog expediting his death,” it added. “Rabid dogs like Baiden can hurt lots of people if they are allowed to run about. They must be beaten to death with a stick, before it is too late.”

North Korea's pervasive leaders: the Kim portraits Show all 16 1 /16 North Korea's pervasive leaders: the Kim portraits North Korea's pervasive leaders: the Kim portraits In the Democratic People's Republic of North Korea, portraits of former supreme leaders Kim Il Sung and Kim Jong Il are required by law to be hung in the home, the classroom, the factory and all manner of other private and public places Reuters North Korea's pervasive leaders: the Kim portraits In the classroom AFP/Getty North Korea's pervasive leaders: the Kim portraits In the living room AFP/Getty North Korea's pervasive leaders: the Kim portraits In the maternity ward of the hospital Alamy North Korea's pervasive leaders: the Kim portraits On board the ship Reuters North Korea's pervasive leaders: the Kim portraits At the ballot box Mannen av börd North Korea's pervasive leaders: the Kim portraits In the office AFP/Getty North Korea's pervasive leaders: the Kim portraits On the bridegroom Reuters North Korea's pervasive leaders: the Kim portraits On the Pyongyang subway Reuters North Korea's pervasive leaders: the Kim portraits On a government building Reuters North Korea's pervasive leaders: the Kim portraits In the teacher training facility AFP/Getty North Korea's pervasive leaders: the Kim portraits In Kim Il Sung square in Pyongyang Reuters North Korea's pervasive leaders: the Kim portraits In the home AFP/Getty North Korea's pervasive leaders: the Kim portraits At the military parade Reuters North Korea's pervasive leaders: the Kim portraits In the hall Reuters North Korea's pervasive leaders: the Kim portraits At the Chinese border AFP/Getty

In contrast, the North has credited a “close personal relationship” between Mr Kim and Mr Trump for saving ties between their countries from a destructive pattern of hostility.

The leaders have met three times to discuss improving ties and ending the North's nuclear weapons programme.

Mr Trump backed a previous personal attack on Mr Biden by the North and dismissed criticism that he was siding with a foreign dictator over a fellow American.

In May, North Korea had called Mr Biden “an imbecile” for criticising its leader.