The Sudanese army says a military plane crashed Sunday outside the capital, Khartoum, killing 13 people and injuring nine others.

A military spokesman told state media the crew of the Antonov 12 transport plane reported engine trouble before it went down in a rural area.  

He says the plane was carrying military equipment and personnel from Khartoum to El Fasher in the strife-torn Darfur region.

The crash is under investigation.

Government forces have been battling an insurgency in Darfur since 2003.