Speaking at the Arabian Hotel Investment Conference, Paul Griffiths, who started work at Dubai Airports in late 2007, said there was an "assumption that Dubai would have two airports".
"I'm not going to speculate," he told the conference, "but the ability to cater to 150 million passengers is key."
In 2007, 34 million passengers used Dubai International Airport. Terminal 3, due to open later this year, will double its capacity to 70 million.
Al Maktoum International Airport (JXB) in Jebel Ali will be able to handle 150 million passengers once complete.
By 2015 - by which time JXB is expected to be fully operational - Griffiths said 70 per cent of people using Dubai airports will not even set foot in Dubai; they will be transferring to other cities.
Griffiths, who previously ran BAA's London Gatwick Airport, also insisted that Dubai International Airport's Terminal 3 "will open when it's ready".
Commenting on the "disaster" of London Heathrow's Terminal 5, he said: "Thousands of people worked for years or decades on Terminal 5 and were let down a number of small initiatives on the day.
"You only need a few failures in a large and complex process. If you can avoid a big bang like T5, you should. Any project is only going to be as successful as its smallest bottleneck.
"If you can't make a deadline, what is better: changing the date or this kind of disaster? This is why Terminal 3 will open when it is ready."
There have been several delays to the opening of T3 and it is currently scheduled for the fourth quarter of 2008.
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