POLICE are appealing for information following the aggravated break-in and attempted sexual assault of a woman at Wollongong on Sunday.

An 18-year-old woman was at her unit in Smith Street, Wollongong when she was confronted by a man armed with a knife about 3.30am.

He threatened the woman and held her down before attempting to sexually assault her. The woman screamed out for help and the man fled.

The man stole a mobile phone before running out of the unit and heading north across Smith Street.

The woman, who was not physically injured during the incident, described her attacker as being aged in his mid 20s with a tanned/dark complexion. He was 175-180cm tall with a medium build, short dark hair, brown eyes, a wide flat nose and wearing a distinctive black t-shirt with a block style coloured pattern on the front.