JACK Lonie has signed a two-year contract extension that will keep him at St Kilda until at least the end of 2020.

As reported by AFL.com.au earlier this week, the 22-year-old is now locked in as a Saint for the next two seasons after an impressive second half of 2018.

"The way Jack attacked his footy in those few weeks was impressive and a clear indicator of his personality and commitment to the club," Saints list manager James Gallagher said.

"His footy nous and ability to read the play and be creative are among some of the reasons we drafted him in the first place, and he really took his opportunities to display those talents at a critical time.

"Jack is a popular player among our group and an important part of the next generation of players to take our club forward."

AFL.com.au understands that Lonie was initially offered a one-year deal by the Saints. 

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He fielded interest from Collingwood and Carlton, even meeting with Pies coach Nathan Buckley, while seeking the security of a long-term deal.

But the Saints confirmed his new contract on Thursday, the day after the NAB AFL Trade Period.

He has been overseas with his teammates celebrating the wedding of captain Jarryn Geary in Portugal and is expected to arrive back in Australia in the coming days.

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"I'm really excited to have signed on for a further two years," Lonie said in a statement.

"This season didn't turn out how we'd hoped, but there's no one more passionate about turning it around next year than us.

"I really believe in what we're doing here at the Saints and that this group is capable of some real success, and I’m looking forward to being part of it."