St Kilda young gun Max King has reportedly agreed to a massive four-year contract extension, reports The Age's Sam McClure.

Already contracted until the end of 2022, the Saints have moved to lock away their budding star until 2024 on a deal worth north of $3 million, per the report.

It is believed that the deal was done a week ago and now holds off any potential rival offers to lure the emerging key forward.

King, who turns 21 in July, has booted 13 goals from eight games this season, including a career-high bag of five against West Coast in Round 4.

BRISBANE, AUSTRALIA - AUGUST 01: Max King of the Saints celebrates a goal during the round nine AFL match between St Kilda Saints and the Sydney Swans at The Gabba on August 01, 2020 in Brisbane, Australia. (Photo by Jono Searle/AFL Photos/via Getty Images)

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He has played 26 games for the Saints since being drafted out of the Sandringham Dragons with Pick 4 in the 2018 AFL draft.

It has long been thought that the young Saint will one day look to unite with twin brother and Gold Coast Sun Ben King, with the pair being very close and playing all their junior football together.

Ben is contracted to the Suns until the end of 2022, but as he does not yet qualify for free agency, would need to be acquired via trade.

Having locked away Max's long-term future at Moorabbin, it could now create speculation that St Kilda will look to lure Ben in the next 16 months.