O'Neill said: "Gareth Barry still has two years of his contract left to run and from my two years' experience of working with him, he's not one who would be wanting to break contracts lightly.
"I don't want to be in a position of letting really good players go. Gareth Barry is a really good player who still has two years left on his contract.
"I haven't discussed these things with him yet. At some stage obviously I will do. But the day before probably our most important game of the season is not the time to be discussing it.''