Cuts to workers’ basic pay and conditions risk doing long-term damage to local authorities’ credibility as an employer, Unison has warned, as further regional strikes are announced.

Disputes over pay and conditions are ongoing with several authorities, and Unison said its lawyers were now considering if the councils’ behaviour was in breach of EU legislation.

The union claims that giving workers 30 or 90 days’ notice of a change in terms of employment was exploiting legislation intended for redundancies, and not pay negotiations.

Council workers announced strike action over the issue for the 21 September in Birmingham to coincide with deputy PM Nick Clegg’s speech at the Liberal Democrat conference.

Also planned are all-day strikes on 22 September by Shropshire Council workers, and on 6 October, by Southampton City Council social workers.

Heather Wakefield, head of local government for Unison, said the cuts ‘are turning local government into a bargain basement employer which, in future, won’t be able to attract high-calibre staff’.

‘Local authority workers already have the lowest pay and the worst conditions across the whole of the public sector,’ Ms Wakefield said.

Kim Ryley, chief executive of Shropshire Council, said: ‘We are unhappy about the possible disruption of public services that this industrial action poses and will do all we can to reduce the impact on local people – 90% of our staff showed no support for action and we believe Unison’s approach is misconceived and does nothing to modernise public services in a way that local people would like to see.’

Councils have argued cuts to staff pay and conditions will save jobs.