At least 200 prisoners will be allowed to sleep in their own beds over the APEC long weekend of September 7-9 to free up cells after federal and state police asked the NSW Government to make space for the hundreds who might be arrested during the summit in Sydney.

The Attorney-General, John Hatzistergos, said prisoners serving weekend detention would be excluded from their overnight stays but he denied the decision was effectively a "get-out-of-free-jail" card.

Shadow attorney-general, Greg Smith, said it was an appalling decision and other options should have been considered.

"There are sporting stadiums, army disposal areas and other places they could have arranged," Mr Smith said.

"Detention has been carried out in other countries of the world, it has probably been carried out here in wartime and there are temporary arrangements that could have been made that haven't been made."