Allegations of prison rape and extortion have been added to claims against the Mt Eden prison run by private operator Serco, which is already under fire for violence.
Labour MP Kelvin Davis told TV3's The Nation he received at least three allegations of rape and also extortion carried out at the Auckland remand prison.
The Corrections Department took over running Mt Eden yesterday.
After the "fight club" videos and a string of allegations about violent incidents, including a death, the last straw was the revelation that an injured prisoner had been transferred from Mt Eden to another prison.
Today, Mr Davis said he had passed on new information about rape and extortion claims to police.
Mt Eden inmates had been given cellphones and told to call relatives to put money into bank accounts, he said.
He had seen evidence in the form of cellphone numbers and bank account details.
He acknowledged government-run prisons were not safe places either.
"[But] the overwhelming tsunami of information is about Mt Eden Correctional Facility and Serco."
Mr Davis said Serco should not be running any New Zealand prisons.
"We just can't trust the information on these league tables. It's just absolute nonsense ... they are just not credible figures."
He believed the rot would spread to Wiri, the new prison in south Auckland, which Serco will run.
Serco, the international outsourcing company, has a $300 million 10-year contract to run Mt Eden. The contract is currently undergoing a six-year review.