Wages, however, seem to be the stumbling block in Dundee's bid to take the Scotland international striker back north-of-the-border.
"I know exactly how much Mark earns at Portsmouth because I was on the management staff there when he signed from Celtic," said Duffy.
"I also know that Dundee couldn't look at that level of earnings.
"If there is a possibility of getting him then I would be interested.
"But there's nothing I can do until I find out exactly what the situation is."