North Korea has threatened to launch "thousands-fold" revenge against the US after tough UN sanctions were imposed on it following the test firing of intercontinental ballistic missiles.

In a statement on Monday, Pyongyang said the sanctions were caused by a "heinous US plot to isolate and stifle" North Korea.

"We will not put our self-defensive nuclear deterrent on the negotiating table," it said, "and will never take a single step back from strengthening our nuclear might".

UN backs 'toughest sanctions in a generation' on North Korea

The statement, carried by North Korea's official Korea Central News Agency, also threatened to make the US "pay the price for its crime... thousands of times".

It said the UN sanctions would not force the country to negotiate over its nuclear programme or give up its ambitions and warned it would take "action of justice", although it did not elaborate on what that means.


US General: Kim aims to defend with threat

The country's top diplomat, Foreign Minister Ri Yong Ho, said his country had no intention of using nuclear weapons against any country "except the US".

In a speech at the Association of Southeast Asian Nations in Manila, Philippines, he said North Korea is "ready to teach the US a severe lesson with is nuclear strategic force" and added that Pyongyang had already demonstrated the "entire US mainland is in our firing range".

Footage captures 'falling missile' off Japan

It comes two days after the UN Security Council unanimously approved new sanctions to punish Pyongyang, including a ban on coal and other exports worth more than £770m.

US Secretary of State Rex Tillerson has ruled out a quick return to dialogue with North Korea, saying the new sanctions showed the world had run out of patience with Pyongyang's nuclear ambitions.

He said: "The best signal that North Korea could send that they're prepared to talk would be to stop these missile launches."

North Korea: A step closer to war?

Last month, North Korea carried out two intercontinental ballistic missile tests, with leader Kim Jong Un boasting he could strike any part of the US.

A White House statement said US President Donald Trump and his South Korean counterpart Moon Jae-In spoke on the phone on Sunday and agreed Pyongyang "poses a grave and growing direct threat".

Mr Trump thanked Russia and China on Twitter for backing the new sanctions, adding he was "very happy and impressed with 15-0 United Nations vote on North Korea sanctions."