The Malta Union of Teachers has decided to withdraw its membership from the Confederation of Malta Trade Unions.
The union said that this decision, taken by a secret ballot, was final and irrevocable.
The CMTU suspended the union last week following a dispute which started when the MUT proposed the formation of a Trade Union Council just days after all trade unions joined forces to protest against utility rates.
The MUT's proposal was described by CMTU president William Portelli as "untimely". Although the teachers' union took exception to this comment, Mr Portelli would not retract it.
The MUT and the CMTU also differed in their reaction to the final government proposal on the utility tariffs.
The MUT council unanimously passed a vote of confidence in its president John Bencini.