Strike action is set to resume at a north Essex school tomorrow as teachers walk out for three days in a dispute with management.

Members of the NASUWT teaching union have announced a strike as part of an ongoing disagreement with senior managers at Harwich and Dovercourt High School about what they say are unfair and unachievable targets.

Around 30 union members staged a one-day strike on January 15, but called off two further days of action last week after positive negotiations with the school.

However the union now says documents have been circulated by the school which go against the deal made during talks, leaving members with no choice but to resume action.

Chris Keates, NASUWT general secretary, said: “It is regrettable we are now having to proceed with strike action.

“Following discussions last week we believed some progress was being made to resolve the dispute and avoid further strikes.

“However, documents have now been circulated by the school which do not reflect the agreement we considered had been reached.

“Therefore, we have no alternative but to proceed with the planned strike action.

“We remain willing to withdraw the strike action should the employer agree to further discussions and we can reach a position where agreements reached are confirmed.

“I know parents and pupils will be disappointed with this development. Teachers have no wish to disrupt lessons but their concerns must be addressed.”

Dan McCarthy, NASUWT national executive member for Essex, added: “It is deeply disappointing for members that they have no alternative but to take further strike action.

“If the employer agrees to honour commitments made in discussions, further strike action can be avoided.

“All we are asking for is fair and reasonable working practices.”

During the last strike day pupils in years eight to ten stayed at home and carried out online learning.

A spokesman for the school said: “The school has been informed that the NASUWT is to go ahead with its industrial action on Tuesday, January 27, 2015.

“In light of this the school will be open for students in Years 7, 9 and 13 only.

“The school apologises for the lateness of this information. However, the school was awaiting communication from the teaching unions concerned in order to make appropriate provision for students.

“We will keep parents updated about arrangements for Wednesday and Thursday.”

A spokesman for the National Union of Teachers said negotiations with the school about the details of a new policy were ongoing and so it would not be taking industrial action at this time.