One of the most respected members of the Church of Scientology has condemned the leader of the controversial religion, David Miscavige, in an email to 12,000 church members.

Debbie Cook, one of the church's senior members, sent an email suggesting the religion had lost its way under current chairman Miscavige and criticised his aggressive fundraising tactics, which have raised $1 billion for the religion.

The email sent by Cook, who was a prominent figure in the church's Clearwater HQ for 17 years, suggests that Miscavige has strayed from the principles laid down by the religion's founder L Ron Hubbard and advises members to start speaking out against the religion's heavy-handed fundraising policies.

"I have the utmost respect for the thousands of dedicated Scientologists and Sea Org [an association of Scientologists] members," wrote Cook.

"Together, we have come through everything this world could throw at us and have some real impingement on the world around us. I am proud of our accomplishments and I know you are too.

"However," she added, "there is no question that this new age of continuous fundraising is not our finest moment."

Calling on members to form a resistance under the banner "Keep Scientology Working', Cook urged: "We are a strong and powerful group and we can effect a change. We have weathered many storms. I am sorry that no one is telling you, but a new storm is upon is."

Miscavige was accused in the email of heavy-handed fundraising tactics and of spending millions on lavish disused buildings. She accused Miscarvige f acting like a tyrant, violating notions put into place by Hubbard before he died in 1986.

"David Miscavige has now become the 'leader' of the Scientology religion. Yet what LRH (L Ron Hubbard) left behind was a huge structure to properly manage all aspects of the Scientology religion.

"He put a complete and brilliant organisational structure there, not one individual. There never was supposed to be a 'leader' other than LRH himself as the goal maker for our group."

Church authorities have refused to comment.

Miscavige has recruited celebrities such as Lisa Marie Pressley and John Travolta to the religion and was famously Tom Cruise's best man when the actor married Katie Holmes.