ST KILDA has boosted its ruck stocks with the signing of former North Melbourne big man Tom Campbell as a delisted free agent. 

AFL.com.au revealed the Saints' interest in the 30-year-old last month after the club was unable to land Tristan Xerri during the Continental Tyres AFL Trade Period. 

Campbell, who joins the Saints on a one-year deal, was delisted by the Roos after 12 games in three years and will serve as a valuable back-up behind Paddy Ryder and Rowan Marshall. 

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"We’re really pleased to have signed Tom for 2022,” Saints list manager James Gallagher said.

"Stability in our ruck is extremely important for us, and we believe Tom will provide important depth, competitiveness and flexibility to allow us to maintain our structure next season.

"Tom is known for his professionalism and team-first approach and will no doubt be a great influence on our young and developing players."

Campbell began his career at the Western Bulldogs where he played 42 games in six years after being selected in the 2011 NAB AFL Rookie Draft.