The South Korean has been a key figure for the club over the past several years.
Last term, he stepped up after the departure of Harry Kane, but only has a year left of his deal.
Postecoglou told reporters: “Yeah, look, that's not really my area, what I always do and what I've always done is irrespective of the contract situation of players is to you know, treat them all the same. Ben and Sonny are an important part of this football club.
“We've got a really young team at the moment and we need some good experienced players around them and they're two that certainly set the right example.
“And in terms of contracts I think that all gets sorted out at the appropriate time. But from my perspective, and I think the players' perspectives themselves, we're just focused on preparing for a big year.”