The batsman is unlikely to ever to return to the England fold after heavily criticising former coach Andy Flower and a number of teammates in his recent autobiography.
The 34-year-old, who will compete in the Big Bash League for the Melbourne Stars, was dropped by the England and Wales Cricket Board in February following the nation's dismal 5-0 Ashes defeat to Australia Down Under.
"I think it is unbelievable in a way, because certainly he could still be playing cricket for England quite easily," The Guardian quotes Morgan as saying. "It is sad in a way to think that probably the best cricketer I have ever played with is not playing [internationally] any more.
"A guy I have had huge respect for, for a very long time and learnt a huge amount from isn't playing probably as much as he should be."
Morgan will play for Sydney Thunder in the Big Bash League.