Australian ships entered Indonesian waters six times

Australian ships inadvertently breached Indonesian territorial waters six times, a Defence and Customs review has found.

The breaches occurred between December last year and January 2014 and were contrary to Australian government policy and operational instructions for Operation Sovereign Borders.

"On each occasion the incursion was inadvertent, in that each arose from incorrect calculation of the boundaries of Indonesian waters rather than as a deliberate action or navigational error," the review says.

It examined all patrols conducted by Navy and Customs vessels on Operation Sovereign Borders between December 1 and January 20.

Australia has apologised to Indonesia for the unintentional incursions.