An Egyptian court has acquitted two police officers who were previously convicted and sentenced to five years over the killing of a detained lawyer.

Sunday's verdict by the Cairo Criminal Court overturned the earlier verdict against the officers, who were accused of beating lawyer Karim Hamdi to death in February 2015.

Hamdi was detained on charges of belonging to the Muslim Brotherhood, which won a series of free elections after Egypt's 2011 uprising but is now outlawed as a terrorist group.

Mohammed Morsi, a senior Brotherhood figure elected president in 2012, was overthrown by the military a year later, amid massive protests against his rule. Since then, authorities have waged a heavy crackdown on the group.

Rights groups say torture and abuse are widespread in Egyptian detention facilities.