Kevin Federline is reportedly reluctant to hand his two sons with Britney Spears back over to their fresh-out-of-rehab mum until she has proven that she is ready to look after them.

When the couple initially separated last November, Britney had full custody of the boys, Sean and Jayden, with Kevin given visitation right but now the situation is reversed.

A source told Us Weekly that Kevin and his lawyer Mark Vincent Kaplan are “ecstatic” that Britney was released from Promises Treatment Center in Malibu on Tuesday but are “cautiously focused on Britney’s continuing rehab recovery.”

“They are not going to return custody to Britney as a reward for doing her stint in rehab. Kevin’s had the children for six weeks and he will continue to have full custody.”

“Britney has to really demonstrate she can retain sobriety. She was just introduced into a sober lifestyle. Can she maintain it?”

A second source told Extra that Britney’s time with the boys will increase as time goes on: “She’ll have increased custody as long as she demonstrates she’s living life with the best interests of her children.”