The high-level review comes as UN agencies scramble to cope with the fallout from US foreign aid cuts under President Donald Trump that have gutted humanitarian agencies.

The six-page document, marked "strictly confidential" and reviewed by Reuters, contains a list of what it terms "suggestions" that would consolidate dozens of UN agencies into four primary departments: peace and security, humanitarian affairs, sustainable development, and human rights.

Under one option, for example, operational aspects of the World Food Programme, the UN children's agency, the World Health Organization and the UN refugee agency would be merged into a single humanitarian entity, it said.

The memo contains a range of suggestions, some large, some small, some speculative, which, if all adopted, would represent the most sweeping reforms in decades.

It suggests merging the UN AIDS agency into the WHO, and reducing the need for up to six translators at meetings. Another suggestion proposes consolidating the World Trade Organization -- which is not a UN entity -- with UN development agencies.

WTO spokesperson Ismaila Dieng said the body "was established by a separate international agreement and operates independently. It is not part of any ongoing discussions on UN reform".

Matthew Saltmarsh, spokesperson for UNHCR, said the agency had a "unique mandate" in protecting refugees.

One official familiar with the memo called it a starting point.

‘Significant overlaps’

But the language of the internal self-assessment appears to confirm what both supporters and critics of the global body have long said: that the UN needs streamlining. In a series of observations, the memo refers to "overlapping mandates", "inefficient use of resources", "fragmentation and duplication" and notes a bloating of senior positions.

It describes "systemic challenges" the UN faces, problems exacerbated as the General Assembly continues to add missions and programs. "Increased mandates, often without clear exit strategies, and complexities have led to significant overlaps, inefficiencies and increased costs," the document said.

The memo was prepared by a task force appointed in March by Secretary General António Guterres, who said at the time the body needed to make itself more cost-effective.

The task force, considering long-term structural changes, is in addition to shorter-term cost-cutting efforts. Some diplomats have described the effort as a proactive step to help forestall deeper US cuts.

"The memo is the result of an exercise to generate ideas and thoughts from senior officials on how to achieve the Secretary General's vision," said Guterres' spokesman, Stéphane Dujarric.

A Geneva-based ambassador voiced support for the reform ideas. "Anything short of bold and radical at this point will not work," he said, adding that it was time to take a "serious look" at UN staff relocations.

Richard Gowan, United Nations Director for the International Crisis Group, said the radical ideas to merge and slash the UN bureaucracy were generating excitement among diplomats.

"The message from major donors to the UN is that it is time for a very firm shake-up, so big changes may be possible," he said, while predicting some "procedural bickering" and resistance from affected UN entities.

Guterres has long called for UN reform. During a meeting with Trump in 2017, the Secretary General told the US President that the world body was saddled with "fragmented structures, byzantine procedures, endless red tape".

But it is now facing one of the greatest financial crises in its 80-year history. At the start of the year, the United States, by far the UN's largest donor, was already about US$1.5 billion in arrears in mandatory payments for the regular budget and $1.2 billion in arrears for peacekeeping.

Since Trump took office in January, he has cut billions of dollars more in foreign assistance as part of his "America First" foreign policy.

Cuts and geopolitical shifts

The task force memo does not mention any country by name, but notes starkly that "geopolitical shifts and substantial reductions in foreign aid budget are challenging the legitimacy and effectiveness of the Organization".

Among the impacts: the UN humanitarian office, which faces a $58 million shortfall, has cut 20 percent of its staff. UNICEF projects its budget will shrink by 20 percent and the UN migration agency expects a 30 percent budget drop, affecting 6,000 jobs.

The cuts are "having an immediate, devastating impact", Bob Rae, the Canadian ambassador and president of the UN's Economic and Social Council, said on Monday.

The memo also suggests relocating some UN staff from more expensive cities to lower-cost locales, and merging operations in Rome.

Another shorter internal memo sent to senior UN officials last week and seen by Reuters told them to prepare by May 16 a list of jobs that could be performed outside New York or Geneva.

Hundreds of UN staff protested against job losses in Geneva on May 1.

Staff directly supporting the UN General Assembly and the Security Council in New York would remain, the first memo said.