Speaking before a Society of Editors conference yesterday, Lord Patten claimed that "only the press can reform the press".
He said that the "vigour" of tabloid newspapers is "an important part of the liveliness of our democracy", but acknowledged that alleged criminality at the News of the World was "indefensible".
Lord Patten addressed the conference on the day before Lord Justice Leveson's inquiry into press ethics after the phone hacking scandal that led to the closure of the News of the World.
Appeal court judge Lord Leveson will today start hearing a variety of evidence, including testimony from alleged hacking victims such as celebrities and high-profile public figures, at the Royal Courts of Justice in Central London.
In a lecture entitled Ethics and Journalism, Lord Patten hit out at "the sort of criminal behaviour that, it is alleged, was institutionalised at the News of the World".
But he said: "I have no wish to turn our tabloids into trimmed-down versions of The Church Times."
"There is a kind of symbiosis between the BBC and the press. We do different but complementary things," said Lord Patten.
"The BBC depends on the press for some of its news agenda and it gives some stories back to the press to pursue further.
"The style of the tabloids is not something we could or should try to match. But nor should we be snobbish or squeamish about it."
He added: "Free speech... would truly be damaged if a single group of people, beholden to and perhaps even appointed by politicians, were to have the power to decide what should or should not be published."
The former Conservative MP agreed with the likes of Daily Mail editor-in-chief Paul Dacre that there should be some kind of self-regulatory code for the press, similar to the Hippocractic Oath in medicine.
But, he added: "Like free markets, freedom of speech can produce harmful effects if it is completely unlimited.
"It's not helpful if newspapers cite 'free speech' as a blanket justification for every story, every intrusion, every piece of celebrity tittle-tattle, no matter what the circumstances."
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Lord Patten also admitted that the BBC is sometimes unable to pursue news stories if the coverage could be deemed by regulators to have political bias.
"As a publicly funded broadcaster whose output is so directly intrusive, there are some areas where we ought to be particularly careful in our journalism or even decline to follow where newspapers or online journalism may properly lead," he said.
"Despite the BBC's tradition of investigative journalism, it could not have paid for the information on MPs' expenses as The Daily Telegraph did, nor pursued the hacking story at News International as remorselessly as The Guardian campaign did.
"The hacking story inevitably coloured the debate about News Corp's bid for full ownership of BSkyB. That's not something I want to comment on as chairman of the BBC Trust."