The Guinea midfielder made just eight league appearances this season having struggled with injuries.

Liverpool had confirmed his departure in May.

Keita lifted the the Premier League, Champions League, Club World Cup, FA Cup and EFL Cup in his five-year spell in England.

"A number of clubs are obviously going to be interested when a player like Keita is available on a free transfer," said Clemens Fritz, head of scouting and professional football at Werder Bremen.

"He suffered an injury setback at the start of this season and that meant he didn't play as often as he'd have liked to.

"We now want to get him back to his best."