Interim Labor leader Chris Bowen says he didn't realise he was entitled to buy books under his parliamentary privileges.
Mr Bowen was responding to a report in The Australian on Tuesday.
It reported Attorney-General George Brandis had amassed a large book, newspaper and periodicals collection over four years, costing almost $13,000, and paid for by taxpayers.
Mr Bowen, who's been a federal member of parliament for nearly 10 years, said he had only used his publications entitlement for newspapers.
"Members of parliament are entitled to allowances to buy newspapers and magazines (but) I didn't realise you could (use it) for books until I read in the paper this morning."
Mr Bowen said if Senator Brandis had met the guidelines, then his claims were appropriate.
"It's something members will use as they see fit to benefit their ability to garner information," he told reporters in Sydney.
Senator Brandis recently paid back almost $1700 claimed in parliamentary expenses to go to a friend's wedding.