Dozens of British troops are to be sent to Somalia to help peacekeeping efforts to counter Islamist militants, David Cameron has announced.
Up to 70 personnel will join a United Nations contingent supporting African Union troops fighting al-Shabab.
Up to 300 could also be deployed in South Sudan over time.
The PM, who will pledge the support at the UN General Assembly summit, said the approach could help curb migrants coming to Europe.
Somalia’s President Hassan Sheikh Mohamoud is one of several world leaders with whom Mr Cameron will hold face-to-face talks.
Al-Shabab is battling Somalia’s government for control of the country.
British forces deployed there will provide combat training and medical, logistical and engineering support.