United Firefighters Union leader Peter Marshall denied he told Victorian Labor MP Jane Garrett "I am coming to get you" and "you're all f---ing dead" but could face an independent inquiry into allegations he bullied the former emergency services minister.

The state opposition said it was inconceivable Premier Daniel Andrews wasn't aware of complaints about the union leader and accused the premier of lying to Parliament, while the Turnbull government intervened in the bitter dispute by introducing new laws in the Federal Parliament.