Police and prison officials were locked in discussions on Monday over possible strike action if salary negotiations failed in KwaZulu-Natal, Popcru said.

Kwenza Nxele, spokesperson for the Police and Prisons Civil Rights Union, said negotiations were continuing, but with little progress.

He warned if no agreement was reached by Friday, the union would embark on mass action.

"The action will culminate in a national day of action..." Nxele said in a statement.

"The leadership has started from today (Monday) to visit major prisons in KwaZulu-Natal where there will be a mass meeting relating to the programme of action," he said.