Most of the 600 staff in the Greater Merseyside Connexions Partnership are expected to take part in the local action on Tuesday over pay inequalities and plans to increase their working hours.

It is the first strike byConnexions workers since the national service was launched 18 months ago to provide support for 13 to 19-year-olds in and out of school.

The public services union Unison, which represents nearly all Merseyside partnership staff, said that the action was necessary because the management was forcing staff to accept new conditions from April 1.

Roger Bannister, Unison branch secretary for Knowsley, said workers on a 35-hour week would have to work an extra hour and the deal would prolong differences of more than pound;1,000 in annual pay for staff doing the same jobs in different areas.

But Kieran Gordon, chief executive of the partnership, said it planned to make the pay structure fairer and would be offering extra holiday time and a one-off payment to staff whose working week was extended.

The Department for Education and Skills wanted the partnership to fix the dispute quickly. A spokesman said: “It is of paramount importance that Merseyside’s young people receive support from Connexions so we would want to see a quick resolution to the dispute.”