A woman has been sexually assaulted near a bus stop in Melbourne's south-east.

The woman was sexually assaulted about 1am near the corner of Lonsdale and Langhorne streets in Dandenong on August 21.

The man police wish to speak to over the Dandenong sexual assault. Credit:Victoria Police.

The assault occurred beside the Lonsdale Street roadway, about 20 metres from the town hall bus stop, police said.

Police are hoping to speak a teenager, believed to be named Jordan, who may have witnessed the attack.