The Denmark international made 20 Premier League appearances last season but faces further competition in central defence due to the summer arrival of Dejan Lovren from Southampton.
Goal understands that Liverpool have been open to offers for the 29-year-old all summer and Agger admits he could move clubs over the next seven days.
"The future is complicated," he told Jyllands-Posten. "There are a few things that have to be sorted and we have to take it from there.
"I actually don’t know what will happen. It is a bit up to Liverpool. I have had niggling injuries at the wrong times and I have to say that it is difficult to change the team when it is winning.
"I am not frustrated by that. I am frustrated the way it happened and the way it was handled."