The group – known as Anonymous – are part of an online campaign against the belief system, which has its Sunderland base in Fawcett Street.

And the demo was just one of a series held in cities worldwide – including Manchester, Berlin and Amsterdam – to coincide with the birthday of Scientology's founder, U.S. writer L Ron Hubbard.

Demonstrators do not know each other's real names, and hide their faces with masks during protests.

An insider said this is because they fear Scientology-led smear campaigns.

But following a request from police they said they would leave their masks at home during Saturday's gathering.

A Northumbria Police spokesman said this was to avoid members of the public becoming intimidated.

Anonymous says it disagrees with Scientology practices, which it claims include separating members from non-believing friends and family – a process known as disconnection.

And it hit the headlines in January this year when the Church of Scientology launched a legal battle to have video clips of Hollywood actor and Scientologist Tom Cruise removed from the web.

A spokeswoman for the church said: "Since January 17, 2008, Anonymous, a group of cyber-terrorists hiding their identities behind masks and computer anonymity, has targeted the Scientology religion, its churches, leaders and parishioners with hate speech and hate crimes.

"To inform Anonymous members who may be unaware of the criminal acts committed by their leaders, and to prevent others from being misled by Anonymous's propaganda, a video has been produced to provide the facts.

"The video reveals Anonymous's repeated incitements to hate and violence.

"The church has not interacted with these Anonymous individuals nor does it desire to. However, death threats and threats to plant nitroglycerine bombs in churches have made it necessary to take security precautions and identify members of this group responsible for these crimes."

But a member of Saturday's protest insisted: "We just want to give out knowledge".