The Napthine government is backing balance of power independent Geoff Shaw, suggesting an elderly man who was injured in a clash with the MP could be guilty of contempt for blocking his way.

Police are investigating the incident in which John Zammit, 79, was left bruised and with blood on his face after clashing with controversial Frankston MP on the steps of Parliament on Tuesday.

In a surprise move, Speaker Ken Smith appeared to side with Mr Shaw, saying MPs had a right to safely enter and leave Parliament and anyone who impeded that right could be in contempt of parliament.

''It is a contempt to molest a member of either house while entering the house or coming to or going from it,'' he told the house. ''I have concerns … I'm going to make sure … and assure members that I am going to look after their protection.''