Two men pretending to be customers robbed a hawker and cut off a piece of his ear in Butterworth in the Eastern Cape, police said on Saturday.

Spokesman Captain Jackson Manatha said two men dragged the 24-year-old hawker underneath the Butterworth bridge where they stabbed him on his arms, forehead and cut off his right ear.

"As a result a small piece of the ear is missing. They robbed him of money and table knives he was selling," he said.

"The motive of the attack is believed to be pure robbery. It is not clear whether the missing ear piece was taken by the robbers or got lost during the struggle of the robbery."

A case of robbery with aggravating circumstances was under investigation, he said.