Police are investigating two "violent and unprovoked" attacks which they believe could be linked.
Two women were assaulted in Edinburgh city centre over the weekend in a robbery and an attempted robbery said to be carried out by suspects of a similar description.
In the first incident, a man attempted to snatch the handbag of a 40-year-old woman as she walked along East Adam Street at about 5.45pm on Saturday. He threatened the woman with a knife, punched and kicked her before witnesses intervened.
In the second incident, a 31-year-old woman using a cash machine on Forrest Road was forced to hand over money as a man threatened her with a knife.
In both incidents, the suspect is described as male, white, between 5ft 5in and 5ft 7in, with a skinny build and pale complexion with gaunt features and an "unkempt" appearance.
He was wearing a baseball cap possibly, white with dark writing on it, and a pale blue or light coloured jumper with dark horizontal stripes on the body and sleeves.
A police spokesman said: "Both of these incidents were violent and unprovoked assaults, and police are keen to trace the man or men responsible as a matter of urgency.
"Due to the proximity of both areas and the close timescales, as well as the similar description, there is a good chance that the same person is responsible for both incidents, however we will continue to keep an open mind.
"Our Operation Arable officers will be out in the coming days to conduct inquiries, as well as providing a highly visible presence in the area to reassure local residents and visitors.
"In the meantime, we are keen to speak with anyone who may have witnessed either incident or remember a man of this description in the vicinity of either location to contact us immediately on 0131 311 3131, or Crimestoppers in complete anonymity on 0800 555 111."