Labour leader Mr Ruairi Quinn is urging workers in the North to support rallies being organised tomorrow by the ICTU.
The protest has been organised in response to threats against teachers and public service workers and the killing of Mr Danny McColgan.
Mr Quinn said the killing of Mr McColgan and death threats issued by loyalist paramilitaries are "an outrageous attempt to turn the clock back and return Northern Ireland to widespread sectarian conflict."
He said the trade union movement in the North had proved to be an "invaluable bulwark against the sectarianism of the last thirty years." HE added that the intervention of the ICTU was to be "warmly welcomed" and he wished them well in their efforts to protect workers from sectarianism.