A long-running campaign by Somali rebels to block and intimidate foreign aid groups has worsened the food crisis in the East African country, according to a new United Nations report, Reuters says.

The U.N., which recently declared a famine in parts of Somalia controlled by the jihadist group al Shabaab, said militants have burned food and medical aid and killed charity workers.

“The single greatest obstacle to humanitarian assistance in Somalia during the course of the mandate has consistently been the denial of access by armed opposition groups,” principally al Shabaab, the report states.

Al Shabaab said this month that it would lift a ban it imposed last year on outside food aid to ease the crisis, but it maintained embargoes against the U.N.’s World Food Program and some major relief charities.

Plus: In Minneapolis, Somali immigrants are working with local humanitarian groups in a bid to get financial help for their compatriots back home, NPR reports.