A 25-year-old man has been arrested and faces several charges in connection with a sex attack on a show home sales assistant.

The 51-year-old woman was waiting for a client at a show home in the Karaka Lakes development in Papakura, on the southern outskirts of metropolitan Auckland, when she was attacked on March 4.

The woman locked herself in the show home bathroom to escape a knife-wielding intruder who tried to force her to have sex with him.

The man was arrested on Thursday, Inspector Gary Hill of Papakura police said.

"It was fantastic police work - there wasn't DNA used or anything, just really good detective work," Mr Hill told NZPA.

"He's been charged with kidnap, sexual violation, assault and some other charges."

Mr Hill said the woman was traumatised by the attack but had given a very good description of the alleged offender.