The United Nations must be reformed to increase African representation, Secretary-General Antonio Guterres said on Monday when he broke ground on an expansion of the UN's Kenyan campus.

Guterres has repeatedly called over the years for change to give Africa and other regions better representation at the UN.

But this request has made little progress since it requires the five permanent Security Council members – Britain, China, France, Russia and the United States – to agree to dilute their own power.

"We need deeper reforms of... global institutions that reflect the world as it is today, not as it was 80 years ago, and this includes the Security Council, where a historic injustice persists in denying Africa permanent seats," Guterres told reporters.

Reform is 'absolutely necessary'

Asked by AFP for a realistic roadmap towards Security Council reform, Guterres said it would be "difficult."

"But there are some steps already in the right direction," he said.

"It's important to say that reform is absolutely necessary, because with the geopolitical divides we are witnessing, to secure peace and security in the present world is becoming extremely, extremely difficult and we need an effective Security Council," Guterres said.

Guterres was in Kenya to break ground on a $340-million expansion of the UN's Nairobi campus – part of efforts to cut costs by moving staff from its New York and Geneva offices.

'Cheaper' move

"It is a cheaper location than others... It's good business for the UN," Guterres said.

The campus began as a regional hub for the UN's environmental and housing arms but has grown to house more than 80 of its offices and more than 4,000 staff.

Washington has severely cut contributions to the UN under President Donald Trump, and threatened more cuts, putting pressure on the organisation to cut costs.