Workers should prepare for serious battles in Democratic Alliance-led municipalities, Congress of South African Trade Unions general secretary Bheki Ntshalintshali told journalists on Thursday.

"We are calling on all workers, especially municipal workers, to prepare themselves for serious battles after election outcomes have resulted in the DA taking over some metros."

Ntshalintshali said the DA's anti-worker and anti-union policies "automatically" meant that the party could be expected to "unleash a war against workers and purge many of them from municipalities they won".

Ntshalintshali was briefing the media after the trade union federation held its central executive committee meeting last weekend. He said workers had an opportunity to rebuild and ensure that they were organised against the DA.

"We view this as an opportunity to rebuild and ensure that we organise the unorganised workers who will surely become victims of the DA. Cosatu will be leading from the front on these battles."