The Hawaii State Teachers Association and the state are headed to mediation to reach a new contract agreement for public school teachers.

The Hawaii Labor Relations Board on Wednesday approved a request the union made earlier this week, HSTA President Wil Okabe told the Star-Advertiser.

Teachers have been working under a "last, best and final offer" the state imposed unilaterally in July 2011, which will expire June 30. The parties are negotiating a 2013-15 contract.

Under the state’s collective bargaining law, a statutory impasse is declared by Feb. 1 of a year in which an existing contract is set to expire.

A provision of that law allows the parties to choose to enter into mediation, subject to approval by the labor board. The state had requested a mediator from the Federal Mediation and Conciliation Service to help resolve the dispute.

A joint statement by the union and state Department of Education said Gov. Neil Abercrombie, DOE representatives and the state Board of Education had agreed to mediation and that a request to the board had been made.

A DOE spokeswoman would not comment further.

"Because we’re at an impasse, by law, this is the next process," Okabe said.

When talks reached an impasse for the 2011 contract, Abercrombie in August of that year rejected the HSTA’s request for mediation. The parties agreed to federal mediation the following August, but the union ended those talks two months later.

Joan Husted, who retired as HSTA executive director and chief negotiator in 2007, called this week’s move a "very positive development" in the continuing dispute.

"I think the community should be very pleased with the HSTA’s request because it’s one way to get to a settlement, and it’s a very good sign," she said. "There’s a good chance the parties can settle this in mediation."

At issue has been disputes about pay and a performance-based evaluation system tied to the department’s pledged reforms under Race to the Top.

In December, the state had offered teachers 2 percent annual increases over two years, which the union turned down. In January, the state rejected HSTA’s proposal of 4 percent across-the-board increases in each year of a four-year offer.