THE Sydney Swans' trade restrictions continue to bite with the club keen to bolster its ruck division with Brisbane Lions free agent Matthew Leuenberger, but unable to field a competitive offer.

Leuenberger, 27, is set to become a restricted free agent at the end of this season and is understood to have attracted the interest of clubs headed by Essendon and Geelong.

The Swans are also keen to attract a mature big man to support Mike Pyke, who has carried the club's ruck division largely on his own this season, with former Tiger Tom Derickx managing just one senior game to date.

The Swans' ability to recruit players via trades or free agency this year will be severely restricted by an AFL ruling prohibiting them from offering potential recruits more than about $350,000 a season – the AFL's average wage in 2015 – while the cost of living allowance (COLA) is being phased out.

Nonetheless, there had been growing speculation in industry circles that the Swans were keenly interested in Leuenberger and could make a play for the West Australian.

But understands the Swans won't get to first base with Leuenberger given their inability to get close to rival offers that are expected to be at least $100,000 a season higher.

The Swans also have very little flexibility in how they can structure deals for recruits this season.

A League spokesman confirmed that if the Swans were, for instance, to offer Leuenberger or another rival player a three-year contract, the total salary must be capped at an average of $350,000 a season under the trade restrictions.

The Swans are also prohibited from offering a player a one-year deal at the average AFL wage and subsequently re-signing him on another multi-year contract for a much higher amount.

The Swans' trade restrictions will also complicate any trade for their out-of-contract defender Lewis Jetta at the end of this season.

Jetta is considering a move home to Western Australia, and if he ultimately asks the Swans for a trade they will only be able to demand draft picks from West Coast or Fremantle and/or a player prepared to accept a deal of $350,000 a season or less.

Given Leuenberger is a restricted free agent, the Lions have the right to match any rival offer.