'Chelsea offered £42m for Kun and Real Madrid bid £33m for Diego Forlan,' Atletico director Miguel Angel Gil Marin told the Sun.
Related ArticlesJohn Terry models himself on Paolo MaldiniChelsea v Blackburn Rovers: match previewSam Allardyce warns Chelsea over swine fluJoe Cole delighted to be backJoe Cole may hold out on new dealSport on television'If they want a new horizon, Atletico will evaluate it.'
As things stand, Chelsea will not be able to buy or sell any players for the next two transfer windows but an appeal against that has been lodged with the Court of Arbitration for Sport and will be heard before Christmas.
Chelsea were punished by Fifa for inducing Kakuta while he was a teenager to break his contract with Lens.
Atletico have made an awful start to their season both domestically and in Europe.
They recently sacked manager Abel Resino following a 4-0 loss to Chelsea at Stamford Bridge that left them without a point or a goal in three games in the Champions League.
At home they have fared little better and currently lie 15th in La Liga.
Aguero, who has a child with the daughter of Argentina national team coach Diego Maradona, featured in the match against Chelsea and as such could not turn out in the Champions League for another team this season.