Clashes erupted Friday near Muslim Brotherhood\'s (MB) headquarters in the Egyptian capital of Cairo between MB supporters and opponents, state TV reported.Anticipating further clashes between the two sides, a dozen security and armored vehicles were deployed around the headquarters in Moqattam district.Over 20 political parties and movements, mostly liberals, including Al-Dostour Party and Free Egyptians Party, in addition to some 30 public figures, have called for staging a rally dubbed \"Friday of restoring dignity\" on Friday outside the MB headquarters.Anti-MB protesters in the country have been demanding holding presidential election in September under full international supervision, sacking the current government and prosecutor-general, and drafting a new constitution to replace the newly-drafted \" Islamist-dominated\" one.