Martinez also hopes to re-sign Liverpool winger Paul Anderson, telling the Evening Post: "It will probably take a couple of weeks until we can finalise the five players we plan to bring in.
"We are really down the line with three of them while we really need to get a decision soon off Paul and Febian.
"They did really well last season for us - both players gave us something extra in League One.
"But it is not healthy for either parties that the situation goes on for much longer. I would say by Wednesday we have to know either way what is happening.
"That would allow us to have everything in order before we start pre-season training."