Korea Central News Agency (KCNA), which is the mouthpiece of the government in Pyongyang, made the attack in one of two pieces that was aimed at Mr Obama and South Korean president Park Geun-hye.

Both pieces were only in Korean and were not translated into English by the news agency.

One of them was translated by Josh Stanton, who blogs regularly about the North's human rights violations.

He said, in comments about Mr Obama's visit to South Korea made on May 2, KCNA wrote: "Park made waste water-like reckless remarks ... after inviting her American master reminiscent of a wicked black monkey to visit South Korea."

Other attacks in the commentary, according to the Washington Post, described Mr Obama as being "a crossbreed with unclear blood" and like someone who "has the figure of a monkey while the human race has evolved through millions of years".

It also called Mr Obama a "clown," a "dirty fellow" and somebody who "does not even have the basic appearances of a human being".

The US government broke from its usual practice of ignoring the communist country's rhetoric.

National Security Council spokeswoman Caitlin Hayden said: "While the North Korean Government-controlled media are distinguished by their histrionics, these comments are particularly ugly and disrespectful."

In a second piece about Mr Obama, the news agency quoted a series of North Korean workers.

A North Korean monitoring site, NK News, translated one of them as saying: "How Obama looks like makes me disgusted.

"As I watch him more closely, I realise that he looks like an African native monkey with a black face, gaunt grey eyes, hollowed out nostrils, plump mouth and hairy rough ears," the workers was quoted as saying.

He continued: "He acts just like a monkey with a red bum irrationally eating everything - not only from the floor but also from trees here and there.

"Africa's national zoo will be the perfect place for Obama to live (by) licking bread crumbs thrown by visitors."

The second article also featured attacks on the South Korean president, describing her as an "old prostitute".

It is not the first time North Korean media has used such language when talking about the South Korean leader.

Frank Feinstein, who runs the North Korean propaganda monitoring service KCNA Watch, told NK News: "There is no similar instance of this sort of language in the recent KCNA history."