"Didier is somebody we've been watching, and he's somebody we've made an enquiry about," Southgate told the Northern Echo.
"He's a player with definite qualities and he's someone we're interested in, but at this stage of the summer, it's difficult to go any further.
"The one major difference between Didier and a lot of other players is that the signs seem to suggest that his club are willing to sell him.
"That obviously puts him in a slightly different position to some of the other players we might have been looking at.
"When we come back on July 7th to start training, we'd love to have all the players in so we could sit them down and explain exactly how we're going to work this year.
"That would give everybody as long as possible to work together during the pre-season period. If we could do that, it would be a great bonus."