A 64-year-old woman was sexually assaulted as she rode her bike along a quiet downtown Toronto neighbourhood Sunday morning.

Toronto police say the woman was in the area of Spadina Avenue and Baldwin Street when a man she did not know approached her.

She told police she was sexually assaulted during the encounter.

Authorities are asking the public's help in identifying a suspect. The white man is believed to be in his 40s and was wearing a brown sweater with a white T-shirt underneath as well as blue cut-off jean shorts, brown running shoes with no socks and a baseball hat.

Police say the man is about 5'9" with a medium build and an unkempt appearance.

Witnesses or anyone with information are being asked to call the Sex Crimes Unit at 416-808-7474. Anonymous tips can be left with Crime Stoppers at 416-222-TIPS.