The man widely believed to be the Mungiki national leader, Mr John Maina Njenga, and 32 others yesterday denied a charge of belonging to an illegal society.
The Nairobi chief magistrate's court remanded them in custody until March 19 when the case will be mentioned.
The court heard that between February 26, 2004, and March, Mr Njenga became a member of the sect, knowing or having reason to believe it was unlawful.
Ten people charged with Mr Njenga face another count of intending to commit a crime.
Police said that on February 26, at a slum in Nairobi, they were found with machettes, swords and clubs.
It is also claimed that the 33 took an unlawful oath.
The prosecution had asked for two weeks to complete investigations into whether the suspects had participated in robberies and many other crimes countrywide.
The accused were a threat to security, it said, and asked that they be remanded in custody.
In response to the defence lawyers' opposition to the anti-bail plea, chief magistrate Aggrey Muchelule said: "The right of the suspect to liberty, however, is subject to the rights of the larger society to live in a secure environment. The court is alive to the increased armed robberies and cold-blooded murders countrywide.
"Where it is alleged that some members of the proscribed organisation might be taking oaths to commit the atrocities, for the police to get to the root of these activities, the suspects' right to liberty should be compromised for two weeks."
The Mungiki sect had been declared unlawful under the Societies Act Cap 108, he pointed out.
The case will be mentioned on 33 suspects will have spent ten nights in custody by March 19, when the their case will be mentioned.