The African Union called an emergency meeting on its military mission in Somalia on Friday after Washington announced it would end critical funding over the lack of progress against Islamist insurgents.

Somalia has been battling the Al-Shabaab insurgency for around two decades but the Islamist group still controls vast swathes of the country.

The African Union Support and Stabilization Mission in Somalia (AUSSOM) is the leading force supporting the Somali army, providing roughly 12,000 troops.

But in a letter to the AU dated July 1, Washington said it was ending payments to the UN Support Office in Somalia (UNSOS), which provides the bulk of funding to AUSSOM, at the end of this year.

The letter was confirmed by a senior African diplomat to the AU, who said the decision was “irreversible” and the mission is “finished”.