Former federal treasurer Joe Hockey tried to block the release of five-year-old hire car travel details by arguing it could put him at risk by allowing prediction of his movements in a heightened terrorism environment.

The argument was made during a freedom of information battle with Fairfax Media, which on Monday revealed the rules for MPs using privately chauffeured hire cars were repeatedly broken in relation to Mr Hockey's Cabcharge account as shadow Treasurer.

It revealed drivers from a favoured hire car company – Ecotaxi, owned by former policemen Russell Howarth – had filled out and signed on Mr Hockey's behalf Cabcharge dockets worth at least $10,000 from as early as 2009.