This season thee Black Cats have relied heavily on Steven Fletcher, who has scored 10 goals in the Premier League so far.
However, O'Neill has revealed that he would like to lessen the load on the Scottish international if possible.
"I don't want to talk about individuals at other clubs - that's not my remit," he told The Shields Gazette. "But what I would say is that at this stage we do have several irons in the fire when it comes to reinforcing ourselves up front.
"We are looking at a variety of players, not just the one."