The boss of the Berlin zoo made famous by Knut the polar bear has had his finger bitten off by a chimpanzee.

Bernhard Blaszkiewitz, 51, was feeding walnuts to Pedro as he showed a visitor round Berlin Zoowhen the ape grabbed his hand and chomped at his right index finger.

Doctors sewed it back on but said it was not clear whether the operation would be successful.

"Pedro is the boss of the group so he has to demonstrate a certain dominance in it to prove himself," zoo spokesman Andre Schuele said.

"Under normal circumstances, a chimp would never have the chance to reach a keeper or our director."

Blaszkiewitz had previously banned keepers from feeding animals by hand.

The incident would have no repercussions for 28-year-old Pedro, Schuele added.

Berlin Zoo is the home of Knut, who became a worldwide celebrity after being abandoned by his mother shortly after his birth in 2006.

The zoo also hit the headlines in April when a woman jumped into the polar bear enclosureand was mauled just yards away from Knut.

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