New Delhi, Aug 27- Activist Anna Hazare feels "weak and stressed" as his fast for a strong anti-corruption bill entered the 12th day Saturday, said a doctor monitoring his health.

"Anna Hazare has lost seven kg and he is feeling weak and tired," a doctor, pleading anonymity, told IANS.

"Although his vital parameters are stable at present, he should end his fast as soon as possible as his health is deteriorating. His complexion shows his health condition - he has turned dark due to dehydration," he added.

A volunteer confirmed that the 74-year-old activist is "stressed" and is "unable to walk properly".

Hazare has been surviving only on water since Aug 16, when he started his fast and was arrested. He was sent to Tihar Jail and was released the same day but he refused to come out. He shifted to Ramlila ground here Aug 19 where he has been continuing his fast since. (IANS)