North Korean leader Kim Jong Un called Donald Trump “deranged” and said in a statement carried by the state news agency that he will “pay dearly” for his threats.

He said Mr Trump is “unfit to hold the prerogative of supreme command of a country” and described the president as “a rogue and a gangster fond of playing with fire”.

“I will make the man holding the prerogative of the supreme command in the US pay dearly for his speech calling for totally destroying the DPRK,” said the statement carried by the Korean Central News Agency in a dispatch issued from Pyongyang on Friday morning.

DPRK is the abbreviation of the communist country’s official name, the Democratic People’s Republic of Korea.

The statement responded to Mr Trump’s combative speech at the UN General Assembly on Tuesday where he mocked Kim as a “rocket man” on a “suicide mission” and said that if “forced to defend itself or its allies, we will have no choice but to totally destroy North Korea”.

Kim Jong Un described Mr Trump’s comments as “mentally deranged behaviour”.

He said the remarks “have convinced me, rather than frightening or stopping me, that the path I chose is correct and that it is the one I have to follow to the last”.

He added that he is “thinking hard” about his response and that Mr Trump “will face results beyond his expectation”.

In recent months, North Korea has launched a pair of intercontinental missiles believed capable of striking the continental United States and another pair that soared over Japanese territory.

Earlier this month, North Korea conducted its most powerful nuclear test to date, drawing stiffer UN sanctions.

Donald Trump and Rex TillersonUS president Donald Trump and secretary of state Rex Tillerson during the United Nations General Assembly (Evan Vucci/AP)

Mr Trump yesterday announced a new order to help the US target people, companies and banks financing and facilitating trade with North Korea.

He also praised China for reportedly ordering banks to stop doing business with Pyongyang.

Mr Trump said his new executive order would also disrupt other trade avenues for North Korea in efforts to halt its nuclear weapons programme.

He made the announcement on Thursday during a working lunch with Japanese Prime Minister Shinzo Abe and South Korean President Moon Jae-in.

Kim Jong-unNorth Korean leader Kim Jong-un has extended his country’s missile testing programme (Korean Central News Agency/Korea News Service via AP)

Mr Trump said “tolerance for this disgraceful practice must end now”.

He also saluted China’s central bank for what he said was a move to stop its banks from trading with North Korea. That development was reported by Reuters on Thursday.

Moon Jae-in and Donald TrumpSouth Korean president Moon Jae-in urged North Korea to abandon its nuclear weapons and seek dialogue (Evan Vucci/AP)

China is North Korea’s main trading partner and conduit for international transactions, and Washington has been pushing Beijing to scale back economic and financial ties to further isolate Pyongyang.

Mr Trump, in his address to the UN on Tuesday, said it was “far past time” for the world to confront Kim, declaring that the North Korean leader’s pursuit of nuclear weapons poses a threat to “the entire world with an unthinkable loss of human life”.

The president said: “Rocket Man is on a suicide mission for himself and his regime,” mocking Kim even as he sketched out potentially cataclysmic consequences.

Asked for clarification on Thursday on what circumstances might qualify for the “totally destroy” threat, Mr Trump’s national security adviser, HR McMaster, told NBC that would be if North Korea attacked the US or its allies.