Charlie Sheen has agreed to "co-operate" with Los Angeles Department of Children & Family Services

Charlie Sheen

The 'Anger Management' star - who slammed the organization as "incompetent" after custody of his four-year-old twin sons Bob and Max was awarded to Scott Mueller, the brother of his ex-wife Brooke - feels "frozen out" of the boys' lives now they are no longer in the care of their temporary guardian, his former spouse Denise Richards, and knows he needs to "step up" to change that himself.

A source said: "He has finally recognized that if he wants to spend time with the boys, he'll need to cooperate with child protective services.

"Charlie stood on the sidelines as Denise became the temporary guardian of the boys. That meant that he had visitation almost everyday. Now that Bob and Max are with Brooke's brother Scott, he's been frozen out. He hasn't been able to see them.

"For that to change, Charlie needed to step up and participate."

The outspoken star believes it is important to do what DCFS ask in order to get the level of access to the children that he wants.

The source continued to RadarOnline.com: "He doesn't necessarily want full custody of the boys, but he does wants to spend more time with them.

"Charlie will be a big part of the boys' lives. They are his sons and he wants to do whatever is necessary to make that happen. This is one of the first steps."

Denise renounced her temporary custody of the twins because she felt they were exhibiting "violent behavior" towards her daughters.