Sydney have opened talks on a contract extension with John Longmire as his manager confirmed North Melbourne had made an official approach to lure the premiership-winning coach back to his former club.

The Swans say their relationship with their coach remains "extremely strong" and they will not allow the Kangaroos' job vacancy to affect their timeline in renewing Longmire's contract.

John Longmire's manager has confirmed North Melbourne has made an official approach to the Sydney coach. Credit:AAP

Longmire's manager Liam Pickering revealed on Tuesday morning that North Melbourne president Ben Buckley had contacted him in their hunt for a coach to replace Brad Scott, who left the club last month.

The Herald can confirm Buckley had given a courtesy call to his Swans counterpart Andrew Pridham informing him the Kangaroos were intending to reach out to Longmire's management.