A police spokeswoman said there had been some delays in the investigation due to language difficulties from the victim.
The offender was described as being an unknown race, of average height and solid build, wearing dark clothing and possibly carrying a bag.
Members of the public are asked to report any suspicious activity around Collier Avenue to the Wellington Police on 04 381 2000, or information can be provided anonymously by ringing Crimestoppers on 0800 555 111.