Mills and his agent Neil Featherby met with managing director David Richmond and Leeds' agent representative Philip Morrison.
It is expected The Whites will grant him a free transfer as he is one of the most highly-paid players on the Leeds pay-roll.
Featherby said: "We have had some talks with Leeds United in respect of Danny's future and at this moment in time those talks are still ongoing."
Middlesbrough are still favourites to sign Mills after his successful season long loan at The Riverside.
It is expected The Whites will grant him a free transfer as he is one of the most highly-paid players on the Leeds pay-roll.
Featherby said: "We have had some talks with Leeds United in respect of Danny's future and at this moment in time those talks are still ongoing."
Middlesbrough are still favourites to sign Mills after his successful season long loan at The Riverside.