An Egyptian court ordered the closure of one of Egypt’s last independent news outlets Tuesday after convicting its editor-in-chief of operating a website without a license in a major blow to the country's shrinking press freedom.

The publication, Mada Masr, said its editor-in-chief and founder, Lina Attalah, was ordered to pay a fine equivalent to about $53,400. After the verdict, the judge ordered Attalah detained until the fine is paid.

Mada Masr was one of the few remaining news outlets in Egypt known for investigating corruption, the expanding role of the country's powerful military, and human rights violations in a country where newspapers and television stations are closely controlled by authorities.…