The vocal firefighters union is backing Greens MP Adam Bandt for re-election at the September ballot, joining the National Tertiary Education Union in supporting the party's sole lower house member.

The United Firefighters Union supported Mr Bandt at the 2010 election when he first seized Melbourne from Labor's grasp.

Firefighters union head Peter Marshall says the union will back Greens candidate Adam Bandt in Melbourne. Credit:Angela Wylie

UFU national secretary Peter Marshall – who is a member of the Australian Council of Trade Union executive – said Mr Bandt had been a loyal advocate of firefighters as well as being the union's lawyer for a decade.

In 2011, Mr Bandt successfully introduced legislation to the federal parliament that removed the onus of proof for Commonwealth employed firefighters that contracted certain types of cancers.