CAIRO -- An Egyptian security official says police protesting in front of Egypt's Interior Ministry have set fire to part of the downtown complex.

TV footage shows flames licking up the building's top floors and a huge plume of black smoke filling the sky.

The official says protesters lit Tuesday's fire in the building housing in the ministry's personnel department. It then spread to an adjacent building.

The fire followed a protest by thousands of low-ranking police officers calling for better wages and working conditions.

Mass demonstrations that toppled former Egyptian President Hosni Mubarak on Feb. 11 have set off frequent protests by laborers seeking to improve their lot.