A woman has been sexually assaulted and another punched in the face during a violent early-morning robbery in Melbourne's CBD.

CCTV footage has been released of six men police believe will be able to help them with their inquiries into the robbery, which occurred on March 9 about 3.55am.

Loading

The two women were walking down Queen Street when the group of men approached them, before the women were assaulted and robbed, with the offenders stealing a speaker and tobacco.