Diagouraga's initial month-long spell ends this weekend but Warburton is happy for him to keep getting minutes under his belt, safe in the knowledge he will now be able to recall the midfielder at any time.
Warburton recently recalled youngster Charlie Adams from a loan at Barnet and handed him his Griffin Park debut as a substitute in Tuesday night's win over Tranmere.
He said: "We send players out on loan so they can play. (Adams) has gone out, done really well at Barnet and is back with us.
"Toumani is with Portsmouth and doing well. I want him to stay there and get match fit. We have a lot of games coming up.
"I am delighted for Charlie, there is more to come from him."