The United Nations is at risk of "imminent financial collapse" due to member states not paying their fees, the body's head has warned.
António Guterres said the UN faced a financial crisis which was "deepening, threatening programme delivery", and that money could run out by July.
He wrote in a letter to ambassadors that all 193 member states had to honour their mandatory payments or fundamentally overhaul the organisation's financial rules to avoid collapse.
It comes after the UN's largest contributor, the US, refused to contribute to its regular and peacekeeping budgets, and withdrew from several agencies it called a "waste of taxpayer dollars".
Guterres said the UN had faced financial crises in the past but that the current situation was "categorically different".
