Police are trying to identify a man who they want to question about the indecent assault of three women on a popular harbourside walking and running track at Lilyfield in Sydney's inner-west.

The assaults happened on or near the 7 kilometre Bay Run, which winds around Iron Cove Bay, over three weeks in January and February.

Leichhardt Police Area Command acting crime manager Detective Inspector Ned Gligorevic said the reported incidents were "very alarming" and police believed they were carried out by the same man.

"They've [the victims] all indicated that he's approached them and asked for sexual favours and then exposed himself. At this stage, there isn't actually any physical assaults."

In the first case, a 27-year-old woman told police a man approached her and exposed himself when she returned to her car on Glover Street at Lilyfield after completing The Bay Run about 9:30pm on January 31.

A man has been approaching women on the Bay Run by Sydney Harbour. ( ABC News: Mike Kliem )

Two days later, a man riding a yellow bicycle approached another 27-year-old woman on the track between a reception venue and the Leichhardt Rowing Club about 9:30am, police said.

The man dumped the bike and ran off before the woman asked a passer-by for help.

A third 27-year-old woman approached a man who was walking his dog near the Glover Street Sports Ground, which adjoins the track, and told him she had been indecently assaulted about 6:20pm on 17 February.

The victim did not initially contact police and officers made a public appeal for her to come forward. She has since made a report to police.

Detective Inspector Gligorevic said an unspecified number of other women had also come forward but he was unable to confirm if the cases were connected.

Man has prominent teeth, tattoo: police

Police have now released a phone image of the man they want to speak to over the three assaults.

Rachel Shermer regularly walks on the track with friends. ( ABC News: Liv Casben )

"Through our investigations inquiries we've obtained this image from a witness, and we're hoping that the person depicted in that image will be able to assist us with our inquiries," he said.

Police have described the man as being of Caucasian appearance, aged between 20 and 30, about 180cm tall, with short, cropped hair and brown eyes.

"The most important thing with this offender is that he has very prominent teeth. Our victims have all indicated that and he has a tattoo on his left arm which may be a sleeve," Detective Inspector Gligorevic said.

He said police had put a substantial amount of resources into ensuring that The Bay Run was safe, but it was a timely reminder for women to be aware of their surroundings.

"Look around you as you jog along and there's always safety in numbers."

Malita (L) and Sophia (R) haven't felt unsafe on the track but may be more cautious now. ( ABC News: Liv Casben )

Rachel Shermer regularly walks on the track with friends.

"In recent years I wouldn't do it [the walk] by myself. I would only ever do it with people because of the amount of incidents that we've had particularly up by the football fields.

"You've just got to have your wits about you all the time and it doesn't matter what time of the day."

Two other locals Malita and Sophia were on the path today and had never felt unsafe.

"I think I would just be a bit more cautious and probably just pick the time that I would go. I wouldn't go as late as usual and probably stick with a partner," Malita said after being told about the incidents.

Detectives want anyone with information they have not yet spoken with to come forward.