Pope Tawadros II denounced the Jehovah's Witnesses sect in a television interview on Sunday, describing it as "unchristian".
"The Jehovah's Witnesses sect is unchristian, illegal and originally a Zionist movement," said the head of the Coptic Orthodox Church in a joint interview Sunday night conducted by three Egyptian Christian TV channels.
According to the US State Department's religious freedoms report on Egypt, there are about 1000-15000 Jehovah's Witnesses in the country.
The Coptic Orthodox Church has been vocally opposed to the sect, labelling it a heretic movement with Zionist aims which threatens Egypt's national security. The sect was officially banned in Egypt by a 1960 presidential decree.
Pope Tawadros II also revealed in the same interview that he has called on various churches around the world to unify the date of Easter celebrations, referring to the discrepancy of the dates on which different churches celebrate the same occasion worldwide.
"This would be good for Egyptian Coptic Christians abroad. Unifying the date allows them to attend the Holy Week services," he added.
Easter falls on a different date for Western churches -- Roman Catholic, Protestant, and Anglican -- than it does for Eastern churches because the former follow the Gregorian calendar while the latter follow the Julian calendar.