Defiant workers are accused of politicising tragedy, as they rally over wall collapse The construction union is rallying in Melbourne, claiming there were cover-ups in the fatal wall collapse. Construction workers march in Melbourne over workplace safety, as builders and the government accused them of politicising a wall collapse tragedy. UNIONISTS marching in Melbourne claim there have been cover-ups in investigations of a fatal wall collapse, as builders and the Victorian government condemned their protest. Streets were closed as thousands of construction workers and their supporters marched through the city centre in the name of workplace safety. Starting outside Trades Hall, a crowd spanning about 10 city blocks paused and turned for a minute's silence while facing a Grocon building site along Swanston Street, where three people died last month in a wall collapse. The rally then moved to the Grocon-managed Emporium building site - also the site of a controversial union-led blockade. Some protesters booed before being called to calm by organisers. A banner reading, `Safety for Grocon workers now' was carried at the front of the rally, which also passed WorkSafe Victoria. Dozens of police officers, including some on horseback, watched the rally as many city streets were closed. Grocon has accused the union of using workplace safety concerns to try to "smash" the building company, while Premier Denis Napthine said the rally was an insult to those who died. But CFMEU Victorian secretary John Setka, who has resisted calls to abandon the protest, said the union was doing nothing wrong. He said not enough was being done to probe what happened and punish those responsible for the fatal collapse of the brick wall at a Grocon site in Swanston Street. "It smells of a cover-up, people trying to sweep things under the carpet, which to me is totally unacceptable," Mr Setka said. The rally included a march to the wall site for a minute's silence. Grocon accused the union of manipulating the issue. "In truth this rally is the next phase in what the CFMEU has publicly boasted is `a military operation' to `smash Grocon' because we refused to cave in to its demands to allow CFMEU officials to effectively run our operations," the statement said. Mr Napthine said the union was politicising the issue, telling the ABC: "This is just an insult to those people who died in that wall (collapse). This is an insult to their families. To use that for union political purposes it is a step too far. It is a disgrace and they should desist. The Master Builders Association accused the CFMEU of a "blatant power grab amid an escalating, bitter campaign to undermine one construction company." Mr Setka said he could not understand the opposition to the rally. I think it's an absolute disgrace. The only ones politicising it is them," he said. One of our jobs is to preserve life and that's what we try to do. WorkSafe says its investigation of the causes of the collapse will not be influenced by public pressure. Health and safety director Jarrod Edwards says injuries on construction sites in the state have fallen by 3.5 per cent in the past 12 months. "Victoria has the safest workplaces and the lowest number of injuries in the construction industry of any state in Australia," he said in a statement. The Fair Work Building and Construction regulator warns workers they will be breaking the law if they attend the rally without their employer's permission.