Talks on Sunday between contract bargaining teams representing the New Haven Unified School District and its teachers union were not fruitful, representatives of both sides said Sunday.

The union's 575-600 teachers thus began a planned strike at 7 a.m. Monday, according to New Haven Teachers Association president Joe Ku'e Angeles.

"Unfortunately, today's negotiations did not yield useful progress," Ku'e Angeles said Sunday.

The school district's "last, best, and final offer" is for a 1 percent raise for 2019-2020, as part of the teachers' salary schedule, and a one-time 3 percent payment. A new amendment to that added a 0.5 percent on-the-schedule pay raise for teachers for every additional $1 million in state funding for 2019/20, up to an additional 1 percent raise applied to the salary schedule.

The teachers, meanwhile, are seeking a 10 percent raise over the 2019-2020 and 2020-2021 school years.

The New Haven district includes 12 schools in Union City and Hayward, which the district vows to keep open, using substitute teachers and administrative staff to lead educational activities.