The District plans to allow public charter schools to enter into long-term leases for a dozen old public school buildings, some of which are traditional public schools that are slated to close by next year, Mayor Vincent C. Gray said Monday.

Officials are making available four other buildings for short-term rental by charters and community organizations, with the school system retaining ownership of the buildings, giving the city school system the ability to expand in case of future enrollment growth.

“This process reflects my commitment to helping more public charter schools gain access to appropriate space for their programs,” Gray (D) said in a statement.

The announcement comes after years of complaints from charter advocates that the city hoards its empty school buildings, leaving fast-growing charter schools struggling to find appropriate and affordable facilities.

“We’re pleased,” said Robert Cane, executive director of Friends of Choice in Urban Schools. “This is a large number of buildings we’re talking about here.”

Charter critics said the mayor’s effort to turn over shuttered buildings could fuel the decline of the traditional school system, which has struggled to compete for students in recent years.

When Chancellor Kaya Henderson announced her intention to close 15 schools by June 2014, she cited low enrollment as the primary reason but said she did not anticipate releasing any buildings from her inventory. Now eight of those schools are among those to be made available to charters, fueling activists’ concerns that the school system’s erosion has reached a tipping point.

“It’s beyond worrisome,” said Virginia Spatz, who co-hosts an education-themed talk show on community radio. “We will become a full charter system without ever having had any conversation about that.”

Charter schools are growing quickly and enroll 43 percent of the city’s students.

District residents also have expressed concerns that the loss of neighborhood schools threatens community identity. Charters that take over neighborhood school buildings can draw students from all over the city, while neighborhood children would go to other schools.

Henderson said Monday that she is proud that the process turned around quickly and believes it is in the District’s best interest.

“As a city, we are committed to increasing the number of high-quality seats we offer to families, especially in our high-poverty neighborhoods,” Henderson said in a statement.

Buildings subject to 25-year leases include Langston and Sharpe Health in Northwest; Benning, Hamilton, Ron Brown, Shaed and Young in Northeast; and Ferebee-Hope, M.C. Terrell-McGogney, Shadd, Wilkinson and Winston in Southeast.

Those available for short-term lease are Gibbs, Kenilworth, Mamie D. Lee and Marshall, all in Northeast.

At least two of the schools, Benning and Shadd, house charters on short-term agreements and will become available for long-term leases.

All of the buildings to be released are east of Rock Creek Park, where enrollment losses have been greatest in recent years.

Deputy Mayor for Education Abigail Smith will oversee the process of releasing the buildings for bids. Smith’s office has established a Web site to serve as a clearinghouse for information about the surplus buildings.

Bidders have until June 30 to submit a “reuse inquiry form.” Officials will gauge interest in each facility and then will release a first batch of schools for bids by July 15.

Smith said she anticipates making available between four and seven schools in that first batch, depending on interest. Applicants will be evaluated according to criteria that include academic performance and ability to pay for building renovations and maintenance.

If a building stays vacant, it could be released for other uses.

Cane said he hopes the buildings are put in a trust and reserved for educational purposes.

“We don’t think any buildings should be sold off for condos,” he said. “They should be held and maintained by the government for when we do need them — and we will need them.”