Scientology is banned under an Act of Parliament passed in 1969.
Mr. Minchin said there were about 500 active members and the practice was being conducted "quite openly."
The Church of the New Faith had been operating a church for its members in Fullarton since April last year.
Although Mr. Minchin declined to discuss the matter in detail, because it was a "semi-legal matter at this stage," he said one prime objective of the religion was to remove the Act which outlawed Scientology.
"We regard this Act as religious discrimination," he said.
"I think it is a piece of South African legislation and we are working towards the removal of the Act."
The Attorney-General (Mr. King) said last night he had no information that Scientology was being practised in SA.
"The Scientology Act, passed by the last Parliament, prohibited certain practices, but I have no knowledge of whether these practices are bieng conducted here," Mr. King said.
On March 15 the Leader of the Opposition (Mr. Hall) said during a radio talk-back programme that he believed Scientologists were becoming active again in SA.
"I believe they would be breaking the law if they operate for monetary reward and it would be the responsibility of the Attorney-General to adjudicate in that matter," Mr. Hall said.