The former Oasis star hit headlines last month (Jul13) when it emerged he is locked in a court battle with an American journalist who claims he fathered her young daughter.
Neither Gallagher nor his wife, former All Saints star Nicole Appleton, have commented on the scandal, but their marriage seems to be heading to an end after Gallagher hired Fiona Shackleton, the lawyer behind a string of celebrity divorces.
A source tells The Sun, "Hiring Fiona Shackleton is a huge statement of intent from Liam. Divorce had been mentioned but until now nobody knew he would actually go through with it. Now the wheels are in motion.
"Nicole will be devastated. Shackleton is one of the best. She is incredibly shrewd in the courtroom. On top of that, she represented Liam's all-time hero Paul MCCartney. There is every chance this could turn nasty and it looks like Liam will not be giving up his massive fortune easily."
Shackleton helped MCCartney keep most of his estimated $800 million (£533 million) fortune intact when his second wife Mills was awarded $36.4 million (£24.3 million) in 2008. The lawyer also represented Madonna during her split from Guy Ritchie and has recently overseen the quick divorce of her cousin Nigella Lawson and advertising mogul Charles Saatchi.
Gallagher wed Appleton in 2008, seven years after the birth of their son, Gene.