The Abbott government has tripled the amount of money spent on the large orange lifeboats used to tow back asylum seekers breaching Australian waters to Indonesia to $7.5 million as part of its tough border control policy.

The figure, to be revealed at an estimates hearing on Friday, is $5 million more than the initial $2.5 million allocated to purchase lifeboats in January.

An empty lifeboat that carried asylum seekers back to Indonesia from Australia. Credit:AFP

It is believed each lifeboat costs about $200,000, which means the lifeboat fleet has increased from 12 boats to about 37 boats, each of which are only used once.

According to documents obtained by Fairfax Media $5.7 million will also be spent on an Australian Maritime Identification System, intelligence gathering technology that aims to locate ''security threats'' on the water before they reach Australian shores.