United Nations Secretary-General Antonio Guterres (left) and US President Donald Trump pose for a photo prior to a high-level UN reform meeting at the UN headquarters in New York, Sept 18, 2017. [Photo/Xinhua]

Guterres and Trump made their remarks at a high-level UN reform meeting in New York.

Guterres said that efforts were needed to change "fragmented structures" and "byzantine procedures" in the UN, making it a more "nimble and effective, flexible and efficient" global organization.

He also mentioned that the UN is making progress on a broad and bold reform agenda to strengthen itself.

"We are pursuing sweeping management reform -- to simplify procedures and decentralize decisions, with greater transparency, efficiency and accountability," Guterres added.

Meanwhile, reforms on UN peacekeeping operations and the development system, as well as strategies to achieve gender parity and end sexual abuse, were also underway, noted the UN chief.

Addressing the meeting, Trump said that the United Nations has been kept from reaching its full potential because of bureaucracy and mismanagement.

He praised Guterres for laying out a vision to reform the UN, noting that there has been changes under the secretary general.

In his speech, Trump pointed out that the United Nations on a regular budget has increased by 140 percent, and its staff has more than doubled since 2000.