Blake Shelton says being responsible for Gwen Stefani's children has been a ''scary moment'' for him.

The 'God's Country' singer has been dating the No Doubt frontwoman for five years and he loves looking after her three children - Kingston, 14, Zuma, 11, and Apollo, six.

Speaking to Entertainment Tonight, he said: ''It's been a scary moment for me. It's one thing to be with the kids all the time and be their buddy but you do have to consider after a while that they start to listen to things that you say. There's a lot of responsibility that comes with that which is new to me.''

Gwen had previously gushed over Blake's ability to be a ''good'' father figure to the three children.

The singer said: ''He is a good dad, actually. He's been helping me out a lot. I literally get to the point where I'm like, 'You gotta get home - I need help!' It's hard. I got three boys.

''I feel as if I spent the last four years healing - you know, trying to build my life again. Having a best friend like Blake to help me do that has been one of the greatest gifts.''

Blake is a ''fun'' father figure to Gwen's sons.

A source said: ''He's so fun and has shown Gwen's kids another side of life filled with adventure. The boys have really grown immensely by spending time with Blake. They're all very like-minded and comfortable with each other. [Gwen] is much more relaxed and enjoys life more. Gwen has changed a lot since she met Blake, and it's all for the better.''