Regarding Heskey's comments, O'Neill added: "I've been away from my desk for a couple of days, so I will genuinely have to sit down and have a think about it before I make any comment on that.
"There are players at this football club with proper ambitions to be in the England reckoning next summer - and so they should - like Ashley Young, James Milner, Stewart Downing, Gabby Agbonlahor and Emile Heskey.
"But players need to remember themselves here. The World Cup is not next week, not before Christmas and not even before Easter. It's a long, long way away.
"The side picked, if the World Cup was just round the corner, might be a lot different to the one picked for next summer. There could be five changes or more with things like injuries or loss of form."
Heskey joined Villa from Wigan for £3.5m in January, linking up again with O'Neill after a previous spell together at Leicester City.
He has also won 57 England caps since making his debut against Hungary in 1999.
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