SEOUL (REUTERS) - North Korean Foreign Minister Ri Yong Ho called US President Donald Trump's address to the United Nations "the sound of a dog barking", brushing aside Mr Trump's remarks that the United States may be forced to "totally destroy" North Korea.

"There is a saying that goes, 'Even when dogs bark, the parade goes on'," said Mr Ri in televised remarks to reporters in front of a hotel near the United Nations headquarters in New York.

"If (Trump) was thinking about surprising us with dog-barking sounds then he is clearly dreaming."

When asked by reporters what he thought of Mr Trump calling North Korean leader Kim Jong Un "rocket man", Mr Ri quipped: "I feel sorry for his aides."

Mr Ri is slated to make a UN speech on Friday (Sept 22).

His comments were the first official reaction from North Korea after Mr Trump had issued his sternest warning yet to Pyongyang in his address to the United Nations, urging member states to work together to isolate the Kim regime until it halts its hostile behaviour.

If North Korea threatens the US or its allies, Mr Trump said: "We will have no choice but to totally destroy North Korea.

"Rocket man is on a suicide mission for himself and his regime."

South Korea's presidential office had later said Mr Trump's warning to North Korea had been "firm and specific".