US President Donald Trump has been laughed at while addressing world leaders at the United Nations.

But he wasn’t trying to be funny.

Mr Trump was discussing US gains and achievements under his presidency as he opened his address to the UN general assembly on Tuesday (local time).

Mr Trump said the American economy was “booming like never before” and that his administration has accomplished more in under two years than almost any other administration.

His boast sparked laughter from the scores of heads of state and delegates in the audience for the speech.

Mr Trump, who has long claimed that his predecessors’ weak leadership prompted other nations “to laugh” at the US, seemed flustered by the response and said: “I didn’t expect that reaction, but that’s OK”.

Mr Trump said the US was a “stronger, safer and richer country” than when he took office in January 2017.

“We are standing up for America and for the American people, and we are also standing up for the world,” he said.

Some in the audience also grumbled during Mr Trump’s remarks when he said “we reject the ideology” of globalism and criticised nations such as Germany for agreeing to an oil pipeline with Russia.

From ‘Rocket man’ to good guy

The speech came a year after his last appearance at the UN, when Mr Trump derided North Korean leader Kim Jong-Un as “Rocket Man” on a “suicide mission for himself and for his regime”.

But on Tuesday, Mr Trump was full of praise for Mr Kim with praise while he turned his aim on China, Iran, OPEC, the World Trade Organisation, the International Criminal Court and the UN Human Rights Council.

And a year on from thanking China and Russia for their support in backing sanctions against North Korea, the President berated China on their trade policies.

He said the US had already announced $US250 billion ($345 billion) worth of tariffs on Chinese-made goods and was not ready to back off.

“China’s market distortions and the way they deal cannot be tolerated,” Trump said.

JUST IN: Trump opens UN speech saying, "In less than two years, my administration has accomplished more than almost any administration in the history of our country" to which then entire UN general assembly LAUGHS OUT LOUD at the president of the United States.

— Kevin Baron (@DefenseBaron) September 25, 2018

Fox News abruptly cuts off this clip of Trump talking about his accomplishments, right before the audience laughs. https://t.co/gwM4E3YMwp

— Christina Wilkie (@christinawilkie) September 25, 2018

The overriding theme of Mr Trump’s speech was sovereignty, including criticism of globalism.

“I honour the right of every nation in this room to pursue its own customs, beliefs, and traditions,” he said.

“The United States will not tell you how to live or work or worship.

“We only ask that you honour our sovereignty in return.”

He also lambasted “the corrupt dictatorship in Iran” and described how “Iran’s leaders sow chaos, death, and destruction” and plunder Iran’s “resources to enrich themselves and to spread mayhem across the Middle East and far beyond”.

Additional US sanctions on Iran will resume in November, and Mr Trump said, “we’re working with countries that import Iranian crude oil to cut their purchases substantially”.

Mr Trump also said that “OPEC nations, are, as usual, ripping off the rest of the world” and the UN human rights council, which Australia was elected to a year ago, “had become a grave embarrassment to this institution, shielding egregious human rights abusers while bashing America and its many friends”.

“We withdrew from the human rights council, and we will not return until real reform is enacted,” Mr Trump said.

“For similar reasons, the United States will provide no support in recognition to the International Criminal Court.

“As far as America is concerned, the ICC has no jurisdiction, no legitimacy, and no authority.”

-with AAP