Borussia Dortmund have offered a contract extension to Mats Hummels as he contemplates whether it is time to leave the club.

The Germany international has been on Manchester United's list of targets for some time but insists he has yet to make a decision.

Dortmund CEO Hans-Joachim Watzke is optimistic about extending his stay. 'We continue to plan with him,' Zorc told German magazine kicker. 'We will continue our dialogue with Mats regarding our collaboration.'

Mats Hummels (centre) congratulates his team-mates after they beat Hoffenheim 3-2 in the German Cup

Hummels (top right) watches on from the stands as Dortmund reach the German Cup semi-finals

Hummels sat out Dortmund's 3-2 defeat of Hoffenheim in the German Cup on Tuesday night as Jurgen Klopp's side booked a place in the semi finals.

The 26-year-old has two years left on his contract but revealed earlier in the week that he is still undecided over his future.

'There's no particular tendency one way or the other. It's just thoughts going through my mind. It will all become clearer in the coming weeks,' he told Sky.

United are reportedly willing to offer Dortmund up to £30million to sign Hummels, who may be tempted to move in search of Champions League football.

Mats Hummels (right) has admitted he is considering his future at Borussia Dortmund