Bayer Leverkusen's Michael Ballack has admitted that he will be keeping his options open this summer.

The former Chelsea midfielder will be a free agent at the end of the season, with an agreement yet to be reached over fresh terms.

Ballack has not been a regular starter for Leverkusen this season, although interim coach Sami Hyypia recently vowed to use the 35-year-old more regularly between now and the end of the camapign.

Despite the promise of more frequent starting action, Ballack has refused to commit his future to Leverkusen.

"Most important is that we now have a personality in charge of the team who has an idea of how to do things," Ballack told Bild. "That Sami Hyypia handed me a starting chance is no matter, of course. I am yet unaware what the future will be.

"There are many links. Some are even coming right from my agent. It is not the best thing to be in the media with these things every now and then.

"If there is anything to conclude, I will decide. I am the player."

Ballack returned for his second spell with Leverkusen in 2010.