"This is something that we'd rather not revisit at this point in time, " e-mailed Robin Goh, assistant vice president of corporate communications at Singapore's Changi Airport Group.

CNN: STORY HIGHLIGHTS

"MCX will leverage mobile technology to give consumers a faster and more convenient shopping experience while eliminating unnecessary costs for all stakeholders, " said Mike Cook, corporate vice president and assistant treasurer, Wal-Mart.

ENGADGET: Best Buy, Walmart, Target, more join forces for MCX mobile payment, deals provider