Ayres made the remarks on the day the Bombers announced they had verbally committed to their first batch of state league players for the NAB Challenge, a group that includes Port's James Magner.

Former Demon Magner, Sandringham pair Clint Jones (ex-St Kilda) and Mitch Brown (ex-Geelong), and SANFL players Jared Petrenko (ex-Adelaide) and Mitch Clisby (ex-Melbourne) were all approached by Essendon recruiting manager Adrian Dodoro, and are set to line up in Morwell against the Saints in the Dons' NAB Challenge opener on March 7.

Coburg key defender and former Collingwood rookie Michael Hartley is also believed to have been looked at by the Bombers.

Ayres, an assistant coach at Essendon under Kevin Sheedy, said that while he would support untapped VFL talent being given a go during the pre-season, the premiership season was another matter.

"Home and away games would obviously cut across the season, so we wouldn't be handing over any of our players at the demise of our season proper," Ayres said.

"The agenda that we would obviously be going into is having the best players available for Port Melbourne to compete in the 2015 VFL season.

"I think if you asked a Port Melbourne player, they would say our first duty is to represent Port Melbourne, not to assist Essendon in the home and away games."

Essendon has been left depleted by the absence of 25 players from its 2012 list, 17 of whom are provisionally suspended pending the result of the ongoing AFL anti-doping tribunal hearing. Eight others have withdrawn in order to maintain the anonymity of the affected players.

The AFL announced on Monday that two different sets of rules would be applied for the NAB Challenge and the home and away season. Essendon can use any players from state league clubs during the pre-season series, however will be restricted to using players who have been on an AFL list in the past two seasons in the event that suspensions linger into April and beyond.

With the Dons also set to use eight to 10 of its VFL-listed players in the pre-season series, there remain about five spots available for other state league players to fill in the NAB Challenge.

Ayres also believed that giving preference to AFL players was "denigrating" to their VFL counterparts.

While the Port coach looked to protect his club's on-field interests, Zebras general manager John Mennie said his club would not stand in the way of Brown or Jones.

"It's their call whether they go to Essendon as one of their top-up players. We believe Mitch Brown is very keen and we'd be keen for him to do it because it gives him an opportunity to get picked up in the future. Clint Jones is a little bit older, so Clint will make up his own mind on what he wants to do," Mennie said.

Werribee chief executive Mark Penaluna also said he would give his blessing to Tigers' VFL players who had the chance to head to Essendon.

"As we've done in the past, we've done everything for the players who are playing for our club to go to another level," Penaluna said.

"The likes of Micky Barlow, Benny Brown and Dale Morris, who are all playing in the AFL. We understand that it's part of our charter, and guys go to the AFL with open arms."

Specifics about the contracts of the short-term Essendon recruits/ players are sure to be discussed at a meeting of VFL club general managers at Visy Park on Wednesday morning.

Clubs will also be seeking clarification on the status of Essendon's three scheduled VFL practice matches, the first of which - against Williamstown on Friday, March 13 - coincides with the AFL Bombers' second NAB Challenge match against GWS.

Meanwhile the Western Bulldogs have confirmed forward Stewart Crameri will sit out the first two weeks of the NAB Challenge due to his provisional suspension. The club is hopeful that the anti-doping tribunal will have handed down its decision by the time of its third match against Collingwood on March 21.

The Bombers have also announced the signature of former Geelong VFL player Mark Corrigan as the club's new development coach.