However, the club have now issued a statement confirming they are in talks with Bennett over a possible loan move.
Posh are likely to be seeking an initial three month loan deal for Bennett with a view to making the move permanent in the January transfer window.
"The club can confirm we are in negotiations with Grimsby Town centre-back Ryan Bennett," a club statement read.
"However, he has not trained with us and a deal will not be finalised on Thursday."