Eritrean satirical cartoonist Biniam Solomon, also known by his pen name Cobra, has been released after spending 15 years in detention without charge in Asmara, Eritrea.

Solomon, arrested in 2011, had never been tried. The reasons for his continued imprisonment were not made clear.

During his detention, Biniam had no contact with his family and received only occasional medical treatment. The authorities did not explain the reason for his release.

Biniam was known for his sharp cartoons criticizing political and social issues. His work appeared in Eritrean newspapers during a brief period of media freedom.

The government closed the private press because it was "endangering national security," and several journalists were jailed.

Human rights groups have long accused Eritrea of detaining thousands of people without trial, allegations the government denies.