Los Angeles Unified School District teachers voted overwhelmingly to authorize a strike if labor negotiations continue to stall, union officials announced Friday evening.

United Teachers Los Angeles said 98 percent of its members who cast ballots voted in favor of a strike.

Members of the union began voting Aug. 23, and ballots were collected through Thursday.

The vote does not automatically mean a walkout will occur. The vote only gives union leadership the right to call a strike depending on the status of labor talks with the district.

The negotiations have been deemed to be in impasse, and a state mediator has been appointed in hopes of resolving the deadlock.

But no mediation sessions have occurred, and none are scheduled until Sept. 27. The late date has led to accusations by UTLA that district officials have been delaying the process, with the union claiming it was prepared to begin mediation by mid-August. The district has denied the allegation, saying it accepted the Sept. 27 offered by the state mediator.

In announcing the strike authorization, UTLA Secretary and Negotiation Chair Arlene Inouye said she hopes the "overwhelming" support of the union membership will convince the school district to agree to move up the start date for mediation.

The District responded to the strike authorization with a statement that expressed hope a new contract agreement can be achieved without a strike.

"L.A. Unified remains willing to explore any avenue which helps resolve the issues for the benefit of our students, families and communities we serve," the statement read in part. It did not specifically address the union's push to move up the start of mediation.

No strike could be called before mediation has been tried.

Los Angeles teachers have not struck in nearly three decades, since a 1989 walkout that lasted nine school days.

The impact of a new strike would be widespread, affecting more than 900 schools and nearly 700,000 students across Los Angeles and 33 other surrounding cities.

Meanwhile, both the district and the union have filed charges against the other with the state Public Employment Relations Board. The union filed an unfair labor practice charge against the district on Monday night, accusing the district of unlawfully interfering with the union's strike-authorization vote and failing to provide requested financial documents.

The district followed suit the next day, accusing UTLA of engaging in "take-it-or-leave-it bargaining" and failing to even consider any compromises for roughly 16 months.

Salary is one part of the division between the district and the union.

United Teachers Los Angeles has asked for a 6.5 percent raise retroactive to July 1, 2016, with the possibility of future raises in a contract that would run through June 30, 2020.

The district has indicated it is "prepared to offer" 6 percent, stretched out over a three-year period. Other district employee unions already have settled for about 6 percent, spread out over several years in various ways, but they could be entitled to additional compensation if the teachers get more.

The union has also called for steps to reduce class sizes, to increase accountability for charter schools, and veto power over proposed conversion of existing schools to magnet schools.

The district has contended that the union's offer would increase the LAUSD's existing $500 million deficit in the current school year by another $813 million. It also claims that the district's existing $1.2 billion reserve fund cannot be used to cover the union demands since it is already being used to offset the existing budget shortfall.

The district released this full statement:

"Following the Board of Education's statement at the Board meeting on Aug. 21, L.A. Unified remains opposed to a strike and stands with students, families, and employees to ensure learning and safety come first.

Students and families will bear the brunt of a strike. We hope our shared responsibility to put students first will prevent a strike and lead to a common sense resolution that recognizes the hard work of our employees while addressing the safety and instructional needs of students and the financial solvency of L.A. Unified.

The Public Employment Relations Board has set the date for mediation on September 27, 2018, as prescribed by California law, and we are looking forward to reaching an agreement. L.A. Unified remains willing to explore any avenue which helps resolve the issues for the benefit of our students, families and communities we serve.

L.A. Unified has reached agreements with labor partners which represent more than 60 percent of the District’s employees, which include salary increases totaling about 6 percent and we are prepared to offer the same to UTLA members.

We are committed to reaching fair contracts in a transparent and thoughtful manner and invite families and communities to learn more about where things stand in the labor negotiations by checking out “Just the Facts” on the L.A. Unified website.

While we work toward a resolution, let’s remember our schools are about teaching and learning. We want to keep the labor discussions out of our schools so the focus can remain on our students."