The Babyshambles rocker allegedly spent the night with a South African brunette called Lindy last Thursday (28.06.07).
Pete met Lindy at London's Crystal nightclub and the pair were seen "kissing and cuddling" as they drank champagne, before leaving together at 2am.
A source told Britain's Sunday Mirror newspaper: "When he first arrived Pete was showing off, standing on his chair and dancing like a loon. Then he started talking to a girl in a revealing white dress. She had the same pointy features as Kate.
"They went up the street for a while then came back inside where they had an intense chat for ages. There was lots of flirting and laughing. Then we saw four of them get into a cab and head off."
The pair reportedly spent the night at Pete's friend's house, where they "disappeared into a bedroom together".
Pete partied with his managers Andy and Adrian and a friend called Purple following a row with Kate, 33.
The source added: "Pete and Kate had a serious argument during the week and he decided to go out. Kate was calling around to see if anyone knew where he was. Hearing about him spending the night with another girl will eat her up."