Rudge Said: "We want to improve the side, so have a few positions to fill. We are talking to other players, but centre-back is clearly a priority."
"We have been to the PFA offices to look at the list of players who are available and there will be a few more looking for clubs," Rudge added.
"The best players will be all right and those with two or three clubs interested in them will look at their best options."
"We would be interested in signing Ade because I think he would do well here, but I would say it was out of the question.
"Palace would want a fee as he still has two years left in his contract and I do not think many First Division clubs would be in a position to take him."
Palace signed Akinbiyi only last year for a fee of £2.2M, something which would be highly reduced now but Akinbiyi would also need to be willing to take a drop in salary of up to 3 quarters of his current earnings.
Ade is believed to be earning 4 times more than City's top paid player and financial constraints mean his signing would be unlikely.