North Korean officials are demanding handwriting samples from thousands of residents in Pyongyang after graffiti appeared calling King Jong Un a 'son of a b****.'

The message, 'Kim Jong Un, you son of a b****. The people are starving to death because of you,' appeared on the walls of an apartment building in the Pyongchon district on December 22, according to news site Daily NK.

The offensive scrawl comes amid a severe famine made worse by recent flooding and the closure of the northern border with China due to the Covid pandemic.

The graffiti appeared as high level meetings of the ruling Workers' Party of Korea were taking place in the capital.

It was soon scrubbed off the walls by local officials and police are working to track down the perpetrator.

Officers have been going door-to-door to nearby homes and businesses to demand handwriting samples and question locals about their movements on the day the message appeared.

The furore was reported to Seoul-based news site Daily NK by a network of undercover 'citizen reporters' in North Korea and China from which it gains information about the closed state.

Police are likely to be using the thousands of CCTV cameras which Kim has installed throughout the city, the site reported.

Criticism of Kim or the regime is strictly forbidden and those who dissent against his tyranny are likely to face long sentences at notorious forced labour camps. In serious cases, rebels can even be put to death.