Activists staged a demonstration at the Labour Party conference today against the illegal blacklisting of thousands of workers by construction firms.
Members of the GMB union, including one dressed as the Grim Reaper, protested at a stand in the conference exhibition area in Manchester.
The stunt was held against building giant Carillion, one of the firms targeted by unions over blacklisting.
GMB national officer Paul Maloney said: "This protest is to highlight that none of the 3,213 workers blacklisted have had an apology or any compensation from employers like Carillion who blacklisted health and safety representatives. Only 194 have been informed that they were blacklisted and the rest still don't know.
"It is also to highlight the terrible toll of death and injury in the construction sector and to underline the importance of the proper enforcement of health and safety laws to prevent this carnage."
The GMB believes construction firms will have to pay hundreds of millions of pounds in compensation to thousands of workers on blacklists.
GMB general secretary Paul Kenny said payouts to the construction workers could reach £600m.
Unions are campaigning for apologies and compensation for thousands of workers they say were blacklisted by more than 40 construction firms.
The GMB is preparing to take legal action on behalf of workers whose names have been held on blacklists, often because of their union activities.
The union is also calling for firms involved in blacklisting to be denied contracts in the public sector until they apologise and pay compensation.
The union will raise the issue during a debate at the Labour conference later today.
A spokesman for Carillion said: "We are very disappointed by the GMB's actions this morning at the Labour party conference. They sent out a wholly misleading message about Carillion's health and safety record, and cynically mixed these up with a raft of incorrect and untrue allegations about our alleged involvement in blacklisting.
"Carillion has one of the best health and safety records in the construction industry. Last year, we reported our lowest ever accident frequency rate, with 0.07 reportable accidents per 100,000 hours worked by our employees and sub-contractors. Despite this, any accident is one too many, so Carillion is committed to continuous improvement to prevent problems from recurring."