April 4 (Reuters) - Activist investor Sachem Head has built a 3.6% stake in Delivery Hero and seeks a seat on the supervisory board of the German food delivery company, a source familiar with the matter told Reuters on Thursday.

The news was first reported by Bloomberg, which also suggested that Sachem Head could try to oust Delivery Hero's CEO Niklas Oestberg. Delivery Hero shares were up 11.7% at 1412 GMT.

Delivery Hero said it does not comment on rumours or speculation. Sachem declined to comment.

Delivery Hero this year faced growing investor concerns about its ability to generate cash and repay outstanding debt organically while still delivering both profitability and growth.

(Reporting by Alexander Huebner, Bartosz Dabrowski in Gdansk; additional reporting by Marleen Kaesebier and Eva Papp; Editing by Kirsten Donovan)