Former Liberal Party leader John Hewson says Tony Abbott should be less secretive about his asylum seeker policies, suggesting the Prime Minister give proper briefings to the public and to MPs from other parties.

''I don't know how long you can sustain just stonewalling, to say, 'We are not going to tell you anything','' Dr Hewson said.

As the controversy surrounding the Abbott government's tow-back policy continued on Friday, the Prime Minister again defended his secrecy over the treatment of asylum seekers at sea, saying he would not release information that would help a war enemy.

''If stopping the boats means being criticised because I'm not giving information that would be of use to people smugglers, so be it,'' Mr Abbott told Network Ten.