New York, Sept. 24 -- US president Donald Trump has criticised other countries' migration and climate policies, during a scathing speech to the United Nations that also took aim at the body itself.

The US president told the UN General Assembly in New York it was time to end the "failed experiment of open borders" and claimed UN predictions over climate change were wrong, prompting gasps from the assembly floor, reports BBC.

Trump also made a major shift in his position on the war with Russia, saying Kyiv can "win all of Ukraine back in its original form".

In a post on his Truth Social platform, he said Ukraine could get back "the original borders from where this war started" with the support of Europe and Nato.

In the wide-ranging UN sp...