Federal cabinet minister Mark Butler says a planned national royal commission on child sex abuse may be a combined effort between state and federal governments.
Prime Minister Julia Gillard announced the royal commission last week to investigate how institutions have dealt with cases of child sex abuse, following fresh allegations of cover-ups by the Catholic Church and police.
Ms Gillard expects the terms of reference for the royal commission to be established by the end of the year.
Mr Butler acknowledges that the inquiry may take some time.
"There's no way it will be complete by the time of the next election and it may still be going by the time of the election after that," he told Sky News on Sunday.
Cooperation from state and territory governments was crucial for the inquiry to be effective, he said.
"What we've discovered is that states doing their own inquiries (and) institutions doing their own internal inquiries haven't dealt with this issue sufficiently."
Asked whether the commission could be a joint effort between state and federal governments, Mr Butler said, "That is a possibility, a legal possibility and something that has precedent".