The 39-year-old journalist had profiled Liam in 2010 for a New York Times called, hilariously, "A Night Out With Liam Gallagher." Page Six report that an affair with the rock star started immediately afterwards, resulting in a baby girl, who is now seven months old.
Liam, who is married to All Saints pop star Nicole Appleton, has issued a statement through his rep saying he is "not going to comment on gossip" - but Liza is now suing him for $3 million, wanting child support.
"Liam admitted the child is his in an e-mail, saying she is a beautiful child because she has 'rock star genes'," a source told Page Six.
"Liza met Liam when she interviewed him for the Times and they began an affair. It continued until around three months after the birth of the child. He ended the relationship when she told him she was suing him for child support.
"Liza isn’t after millions of dollars, she is simply seeking child support and no amount has yet been set. If they don’t settle on a figure, the case will go to a public trial, like the one recently between Linda Evangelista and Francois-Henri Pinault."
Liam already has three children to three different women. His daughter Molly was born in 1998 after he had an affair with Lisa Moorish, just one week after marrying actress Patsy Kensit. He went on to have a son, Lennon, with Patsy in 1999, although their marriage was well and truly over by then.
He met current wife Nicole in 2000, welcomed son Gene in 2004, and tied the knot in 2008.
In a 2008 interview, Liam (who now fronts rock band Beady Eye) bragged about how he has forsaken his rock star past to be a "top dad".
"Once you get your missus pregnant, you’ve got to step up to the plate," he said at the time. "Family’s the most important thing."
We can imagine how his wife feels about this little bombshell... pretty similar to the guy who attacked Liam on stage earlier this year:
More infamous paternity dramas in our Who's Your Daddy slideshow!