Alexandria police on Sunday referred a well known activist to prosecutors on charges of possession of material "insulting the armed forces," reported Ahram Arabic news website.
Police arrested Safwan Mohamed, a leading member in the liberal Constitution Party, at a checkpoint in east Alexandria after they found a sticker on his bag saying "No to Military Trials."
Safwan was among the first Egyptians who signed a 2010 petition supporting the efforts of Mohamed ElBaradei to demand reform from then president Hosni Mubarak. He also ran for parliament in his home district against two prominent Islamists in the 2011 parliamentary elections, but lost.
In recent months, police have arrested scores of individuals on charges of displaying the pro-Muslim Brotherhood "Rabaa sign" in public.
Police have also arrested scores of liberal and leftist activists in recent months, mainly on charges of violating a controversial protest law that restricts demonstrations.