Jude Law's new girlfriend Sienna Miller is clashing with his estranged wife Sadie Frost.

Although Miller and Frost are said to be friends, Sadie has become frustrated by Sienna's attempts to win over her children.

Jude and Sadie have three children together, eight-year-old Rafferty, four-year-old Iris and two-year-old Rudy. Sienna has been showering the children with expensive gifts, which is now coming between her friendship with Sadie.

A source told the Sunday Mirror, "In many ways Sienna's just acting like any step-mum would. She wants the kids to accept her and like her so does her best to treat them.

"Sadie accepts that and realises it's a pretty natural thing to do. But she has been getting a bit frustrated with it all - especially when it comes to Rafferty.

"Sadie wants him to play musical instruments and enjoy reading and playing sport but Sienna has been buying him electronic gadgets. It can be annoying."