UN Secretary-General Antonio Guterres says that he is "totally committed" to reforming the world organisation and it is the best way to get the support of all member countries.

Guterres was especially referring to the Donald Trump administration in the US, which has flung blistering criticism at it.

Speaking to reporters on Wednesday, Guterres said he recognised that the UN needs reforms and he was doing everything "to be totally committed to those reforms".

"Reforms will be the best way to get the support of all member states, including the US and its new administration," he said.

As its largest funder, US Permanent Representative Nikki Haley on her first visit here last week had sternly called for the reforms.

"Everything that's not working, we're going to try and fix; and anything that seems to be obsolete and not necessary, we're going to do away with," she declared.

"Our goal with the administration is to show value at the UN, and the way that we'll show value is to show our strength, show our voice," she said.

Speaking about reforms on Wednesday, Guterres said, "What I am doing is to do everything I can to prove the added value of the UN."

Security Council President Volodymyr Yelchenko, too said that the "UN is far from the ideal" and it is "inefficient in some parts and needs to be reformed".

However, as Permanent Representative of Ukraine, which hold the rotating Council presidency in February, Yelchenko did admit that Guterres was committed to reforms.

He added that he believed that the new Secretary-General would be the one who would be able to bring the changes to the UN.

With anger boiling over in Congress and the administration in Washington because of a Security Council December resolution criticising Israel for building settlements in territories it occupied after the 1967 war, there were threats of cutting US contributions to the UN.

Asked about it, Guterres was nonchalant. "When you talk too much about things that have not happened, you trigger the happening of those things," he said with a touch of humour.

"So one thing you can be absolutely sure is that I will not be making comments on possibilities to enhance the post possibilities to possibly be a reality."