The Philadelphia School District must slash spending immediately, with painful central office and classroom cuts likely for next school year, officials told members of City Council at a Thursday afternoon briefing.

To combat a shortfall of roughly $40 million for the current school year, there will be immediate freezes in hiring and discretionary spending. Top officials, including Superintendent Arlene Ackerman, will take between six and 10 days of unpaid leave, according to people who attended the meeting.

The district's budget totals $3.2 billion.

An Inquirer reporter attempted to attend the briefing, but was asked to leave by a Council staffer, who said district officials did not want the press present.

A school district source put the total gap for this year at $36 million and the gap for next year at about $490 million.

Another round of cuts for the 2011-12 budget year will mean increased class size, those present said, plus a 30 percent reduction in the central office budget, school closings or consolidations, a reduction in common planning time for teachers, no money for new textbooks, and layoff notices for teachers with less than three years seniority in the district and other workers - though layoffs themselves aren't certain.

District officials told those present at the briefing that those cuts would be necessary due to the loss of federal stimulus funding and the possible impact of school vouchers and a lawsuit that could remove caps on charter school enrollment.

Further cuts would be necessary if state funding decreased, a move many think is likely with a Republican governor and a legislature that has made it clear it thinks Philadelphia schools have received too much money in the past.

Those cuts would mean an additional 20 percent reduction in central office budget; more unpaid leaves; cuts to athletics, art and music; and less money for student transportation.

Ackerman warned officials at the briefing that if the district moves backward, the city will, too.

Councilman Bill Green, who last year criticized the district for relying on federal stimulus money to fund recurring costs, reiterated that theme.

"The only people who didn't see this coming was the school district," said Green, who attended the meeting.

Still, Green said, the district's plan appears to be one that minimizes impact to the classroom as much as possible.

And, Green said, "I'm hopeful that we can help them stave off cuts as much as possible through our state and federal advocacy."

Ackerman, Deputy Superintendent Leroy Nunery and Chief Financial Officer Michael Masch are scheduled to hold a press conference on the budget at 4 p.m.