Ottawa police are investigating a series of bank robberies by a man or men wearing a Muslim woman's head scarf.

In the latest incident, on Thursday afternoon, a man in a head scarf robbed a bank at Pinecrest Mall in the city's west end.

Const. Katherine Larouche described the dark blue scarf as a hijab and said it covered the robber's mouth and nose. The man, who also wore a long dark blue robe, handed a Scotiabank teller a note around noon, demanding money.

The robber then fled the bank with an undisclosed amount of cash. No weapon was seen and there were no injuries.

The man is described as dark-skinned and about five-foot-10 inches tall, with a slim build, dark eyes and bushy eyebrows, police said. He spoke English with a slight accent.

Since the summer, there have been at least four robberies, each involving a man donning Muslim women's religious garb. Police were unable to determine whether the same man was involved each time.

"This is not the first time he has hit a bank in Ottawa," Larouche said. "There is no way of saying for sure, but sometimes descriptions given by witnesses bear some similarity and a hijab is sort of out of the ordinary."

Anthony Skinner, acting sergeant in the Ottawa police robbery unit, said his team will piece together reports from the other incidents to determine if the same person is responsible for each robbery.

However, Skinner said, the general stature and disguise lead police to believe it is the same man.

"It [wearing a head scarf] is not something that has commonly been used," Skinner said. "To wear traditional or religious garments to commit robberies is not something that we see frequently, but I wouldn't call it bizarre."