Ballack, 33, joined Chelsea four seasons ago from Bayern Munich while the 29-year-old Cole has been with the Blues for seven years.

Their contracts expired this summer and Chelsea decided against a renewal as they won the double for the first time last season largely without both of them.

Ballack and Cole suffered injuries that ruled them out of large parts of the season.

The German midfielder, who was ruled out of the World Cup with injury, is targeted by several Bundesliga sides including Werder Bremen.

Reports also said that Real Madrid's new manager Jose Mourinho might ponder a move for him this summer.

Arsenal, Manchester United and Tottenham are all interested in signing Cole.