Mirallas has been linked with Tottenham Hotspur and West Ham United in the Daily Mirror and Martinez's comments do little to curb the rumours surrounding his future.
The Spanish boss did reveal that Mirallas has two years left on his contract with the Toffees, rather than just the one which has been widely reported, but admitted that he is uncertain over whether the winger will stick be on his books in 2015/16.
"The total honest truth is that we don't know what will happen in the future," he said. "However, I heard somewhere that he had one year left and it was an unsettled situation, but that's not the case. He has two years left. I think when you see Kevin on the pitch he is someone who brings a real desire to score goals and a goalscoring threat which is quite special."
If Everton do lose Mirallas, it will be a big blow to the side as he is one of their most talented attacking players.
Although the Belgium international's attitude has been called into question on occasion this season, his talent is undoubted and he has a match-winning ability that is hugely valuable to the Toffees.
Mirallas is blessed with creativity, skill and pace and finding a replacement for him would be a tough test for Martinez if he were to move on.
Everton will be looking to be active this summer, after what has been a disappointing campaign this time around, and it will be crucial that they keep hold of the majority of their key players if they are to improve next season.