CAIRO (Reuters) - An Egyptian court on Sunday upheld death sentences for three people for establishing and running a militant group known as Ansar al-Sharia, two judicial sources and state news agency MENA said.

The charges included killing at least 10 police officers and attempting to kill more in a series of attacks between August 2013 and May 2014. The court upheld sentences issued in August. The decision can be appealed within 60 days.

Four people were sentenced to life in prison while seven received 15-year prison terms, the sources said. Nine of the 23 defendants were acquitted.

Egypt has cracked down on suspected Islamists since President Abdel Fattah al-Sisi led the overthrow of former president Mohamed Mursi of the now banned Muslim Brotherhood.

Authorities say a crackdown on dissent and freedoms is directed at terrorists and saboteurs trying to undermine the state.

Death sentences have been handed down to hundreds of Islamists, including Muslim Brotherhood supporters and members.

Last month, 75 were sentenced to death over a 2013 sit-in which ended with security forces killing hundreds of protesters.