The British low-cost carrier said that it was evaluating the opportunity to franchise its brand but did not expect a final decision until early 2007.
"Since it is expected that this will take the remainder of 2006, a decision in relation to this opportunity is unlikely before early 2007," Easyjet said on Friday.
NAS, which wants to set up Saudi Arabia's first private commercial airline, made the approach alongside Dubai-based private equity firm Abraaj Capital.
The fledgling Saudi Arabian airline has applied for a licence to operate domestic flights in Saudi Arabia and hopes to operate low-cost flights to other areas in the Gulf.
EasyJet said it would not invest any equity or cash if it took up the opportunity and a decision would depend on whether NAS gets a licence and whether it would add significant shareholder value.
Stelios Haji-Ioannou, who founded EasyJet in 1995, has extended the orange-coloured "easy" brand to a range of other no-frills businesses, including car rental, finance, leisure, music, men's grooming products and a cruise ship.
NAS is a privately owned corporate jet operator and first announced plans in 2003 to start a domestic airline to compete with flagship carrier Saudi Arabian Airlines.