Brighton terror attacker Yacqub Khayre should have been denied parole for committing arson while in prison, the Victorian Opposition said.

Opposition Leader Matthew Guy cited a key recommendation from a 2013 review that said parole should not be granted to anyone who had failed to behave "satisfactorily" for at least the second part of their sentence.

Yacqub Khayre was in a program designed to counter Islamic extremism in the six months before the Brighton siege. Credit:AP

The government confirmed the recommendation was considered implemented in April 2015.

Mr Guy said that measure should have rendered Khayre ineligible for parole.