AN Australian was attacked and sexually assaulted while she walked home alone during the night in New York, police said.

The 27-year-old was walking near Richardson Street and Kingsland Avenue in Williamsburg, Brooklyn around 2:20am on Thursday morning when a man approached her from behind, pushed her to the ground and sexually assaulted her, The New York Post reported.

After he ran off, she walked almost 2.5km to the NYPD’s 90th Precinct on Union Avenue, where she told police what happened.

The woman, who has been in the US for about four months, was taken by ambulance to Woodhull Medical Centre, where she was listed in stable condition.

Police released a video of the woman being attacked and asked the public for help to capture the man.

Police say he is a black male in the 20s who is about 6 feet tall.

They are also now offering a $US2500 ($A3500) reward for information leading to an arrest.

Residents in the East Williamsburg area say they are shaken up by the attack.