Woman assaulted on Adelaide beach

A woman has been sexually assaulted by a group of men on an Adelaide beach just hours into the new year.

Five men aged between 16 and 20 are believed to have been involved in the assault at Glenelg beach between 2am and 4am on Thursday, police say.

The assault happened just north of the jetty, and police are urging anyone who may have witnessed it to contact them.