Finance Minister Michael Noonan has warned that taped conversations of bankers should not be "mucked about" with for fear of prejudicing criminal trials.
Amid growing calls for explanations about who knew Anglo Irish Bank chiefs were recorded at the height of the 2008 bank crisis, Mr Noonan insisted it was right that Government did not.
He said it was vital that potential evidence is not contaminated.
"The guards are the people who investigate crime in this country and the guards have a statutory right to gather the evidence and other people shouldn't be mucking around in garda business," Mr Noonan said.
"There's a risk of contaminating evidence and contaminated evidence is not admissible in court, so it's very important that what happened, happened - that the guards take everything they wanted to take and they assessed it and provided the basis of files that were provided for the director of public prosecutions."
Mr Noonan made the call after a fortnight of leaked tape recordings and revelations of the cut-throat culture at Anglo Irish Bank.
The former public interest director at Anglo, Alan Dukes, has come under the spotlight. He went on to be chairman of the rebranded Anglo, the Irish Bank Resolution Corporation. Sinn Fein raised concerns about the politically appointed board member - a former leader of Fine Gael - and whether he knew the tape recordings existed.
But Mr Noonan said his former party colleague's job gave him no more legal obligations than any other Anglo director.
"My interest over this is to ensure that evidence isn't contaminated in any way by unauthorised persons interfering with it or accessing it," Mr Noonan said. "So those who are legally entitled to access it should access it and that principally means the guards."
Tanaiste Eamon Gilmore declined to answer who knew what and when about taped conversations and said a planned parliamentary inquiry into the scandal was the way to deal with it.