ACT police investigating indecent assaults at Yerrabi Ponds, Gungahlin

In three separate instances earlier in June, women were approached or grabbed by the man in the evening while walking or jogging by the water.

A 17-year-old woman was the first approached. On Thursday, June 1 at 6pm, the man approached her on his mountain bike before grabbing her.

On Monday, June 5, the man indecently assaulted another woman near the East Island walkway bridge.

Later that evening, the man approached another woman and asked her an inappropriate question but didn't assault her.

ACT Policing's detective superintendent Ben Cartwright said others may have had similar encounters with the man, but didn't consider reporting it to police.

Mr Cartwright said anyone who had been approached, if only asked an inappropriate question, should come forward.

"He may have approached or spoken to people who just thought that was unwanted, not called for and inappropriate," Mr Cartwright said.

"We'd also ask if you are this male person to, please, come to the police station and talk to us rather than us have to come and look for you."

The man was described as unkept, Caucasian, in his late teens or early 20s, of slim build with long hair down over his face.

He was wearing a dark hoodie, blue jeans and a black beanie; when on his old-looking mountain bike, the man would have been wearing a red helmet.

One of women reported the man as having a European, possibly French, accent.

"People have the right to feel safe," Mr Cartwright said.

"[It's] certainly something that members of the public should not have to put up with."

Mr Cartwright said the attacks had not been violent but certainly inappropriate and police will be reviewing old reports to find similar incidents.

"It is a possibility that he's been around for a fair while but it's certainly over the last month or so that things have, kind of, ramped up so we're ramping things up as well."