Former prime minister Paul Keating has savaged a decision to fence off the Domain for 16 days for two Midnight Oil concerts, questioning why front man Peter Garrett would "feel in any way comfortable squatting and profiting from Sydney's central piece of public land".

But on the eve of the first concert on Saturday, Mr Garrett fired back, arguing that if the Domain was good enough for political rallies held by Mr Keating's mentor, former NSW Premier Jack Lang, "it is good enough for Midnight Oil".

Two-metre high fencing, some topped with spikes, was erected around the perimeter of the Domain between NSW Parliament and the Art Gallery of NSW this week and will remain in place until November 21.

Apart from access to paths through the Domain, the public will be shut out from the green space to accommodate successive weekend Midnight Oil concerts.