WASHINGTON — The closings of control towers at 149 small airports, due to begin this weekend because of government-wide spending cuts, are being delayed until mid-June, federal regulators announced Friday.

The Federal Aviation Administration said it needs more time to deal with legal challenges to the closures.

Also, about 50 airport authorities and other “stakeholders” have indicated that they want to fund the operations of the towers themselves rather than see them shut down, and more time will be needed to work out those plans, the agency said in a statement.

The first 24 tower closures were scheduled to begin Sunday, with the rest coming over the next few weeks. Obama administration officials have said the closures are necessary to accomplish automatic spending cuts required by Congress.

Despite the delay, the FAA said it will stop funding all 149 of the airport towers, which are operated by private contractors, on June 15. Under the new schedule, the closures will be implemented at once, rather than a gradual phase-in as had been planned.

Three small airport towers in South Carolina are among those set to close. They are on Hilton Head Island and in North Myrtle Beach and Greenville.

Airport operators in several states, including Florida, Illinois and Washington state, and the U.S. Contract Tower Association, which represents the companies that operate contract towers, have filed lawsuits with the U.S. Circuit Court of Appeals in Washington seeking to halt the closures.

The suits contend that the closures violated a federal law meant to ensure that major changes at airports do not erode safety, and unfairly targeted the program for an outsized share of the more than $600 million the agency is required to trim from its budget by the end of September.

“The administration has decided to make tower closures the poster child of sequestration (automatic spending cuts),” said the group’s director, J. Spencer Dickerson. “We believe there are other ways they could have skinned this cat.”

Federal officials have insisted that the closures wouldn’t affect safety. And there is evidence that with improving safety, some of the closures would make economic sense.

It turns out that the FAA has been using 30-year-old data on aircraft collisions to justify the cost of operating many of the control towers, even though accident rates have improved significantly over that time.

Had the FAA used more current data, it’s probable that some low-traffic airport towers operated by private contractors would no longer have met the agency’s criteria for funding, industry officials said. But the FAA has long been under pressure from members of Congress to open new towers at airports in their states, not to close them.

The FAA began paying contractors to staff and operate towers at a handful of small airports after President Ronald Reagan fired striking air traffic controllers in 1981. Today, there are 251 towers operated by private contractors at airports across the country, at an average annual cost of more than $500,000 each.

The closure plan is unrelated to the FAA’s use of obsolete safety data to justify the contract tower program.