Workers' rights are under threat because of the decision to leave the EU, union activists will warn today.
The Communication Workers Union will say it is clear the Government will try to make workers pay the price of Brexit.
Delegates at the union's annual conference in Bournemouth will call for the rights of workers and unions to be protected under the settlement negotiated by the Government.
Delegates are expected to warn that the decision to leave the EU gives the Conservatives the potential to try to erode the rights of unions to campaign and take industrial action.
Cutting red tape could deregulate the economy, with low wages becoming the norm, the union will warn.
The conference will also debate calls for a cap on the difference in pay between executives and other workers in the public sector as well as in companies wanting to win government contracts.
A new balance is needed between "soaring" boardroom pay and the wages of ordinary workers, delegates will argue.