The Bloomberg administration’s tentative plans to give private agencies more control over some public schools was met with cautious criticism yesterday from education experts and advocates, who recalled failures of similar proposals in the past and called for additional public input.

The plans, which Department of Education representatives emphasized were in very early stages, could involve formalizing the role of private agencies that are currently involved in running small schools, and may include bringing in new groups, including for-profit agencies. The plan’s were first reported in yesterday’s New York Times.

Supporters and critics of the idea said there is little evidence to prove that private agencies are worse at running schools than public agencies — and little evidence they are better. Some critics drew on examples of other cities that have put public schools into the hands of for-profit private agencies.

“They’ve never made a profit. Not only have they not made a profit, they almost went belly up,” a Columbia University professor who studies privatization in education, Luis Huerta, said, referring to cases of for-profit agencies that have managed schools in cities such as Philadelphia and Chicago. “Any time you start to devolve public authority to private interest, the interest of the public good may not be the priority of for-profit private companies.”

Experts on both sides of the issue agreed that any plan should make accountability a priority, but there was little agreement on what that would mean or how to measure it.

Supporters of the privatization plan say that having private agencies running the schools would bring more accountability, because if students didn’t meet standards, the agencies would lose their contracts.

“It isn’t so much regulating the how, but the results,” the policy director for the New York Charter School Association, Peter Murphy, said. “Means is secondary to the discussion.The focus has to be outcomes and how we get more outcomes out of our children.”

Critics of the plan say that it’s just as important to keep track of how agencies run the schools as whether they succeed in the end. Researchers who study privatization worry that public money would go to private agencies that wouldn’t have to report how they spend it, whether they are for-profits or nonprofits.

“They don’t have to open up their books to anybody,” a New York University professor who studies educational leadership, Gary Anderson, said.

An education researcher at Columbia University, Jeffrey Henig, said he wondered about the transparency of other school operations under the plan.

“They’re right to worry about if they’ll have good information about what’s going on in these schools: how you treat kids, how do you maintain open admissions, how do you do a whole range of things that are difficult to monitor when you’ve got a private agency,” he said. “A mix of options can be helpful for a public sector that’s trying solve a tough problem, but here are genuine and legitimate concerns about democratic accountability.”

The vagueness of the ideas had many critics more focused on accountability in the planning process.

“Privatizing public school management is a huge policy shift,” the president of the teacher’s union, Randi Weingarten, said. “There has to be a public debate involving New Yorkers, elected officials, parents, teachers, and others with a stake in making our public schools work.”

The schools chancellor, Joel Klein, said the ideas were still too new and unformed to present to the public for input.

“When I have specific proposals, I’m happy to discuss them,” he said. “We consider lots of things, but that doesn’t mean we’re doing them.”