Jude Law and Sienna Miller were believed to have broken up last night after he was accused of sleeping with his children's nanny.

The relationship between showbusiness's 'golden couple' is said to have been rocky for some time and sources close to Miss Miller say the final straw was when he blamed her for his infidelity.

The 23-year- old actress, who is appearing in As You Like It in the West End, shares a London home with Law. She was said to be in floods of tears after finding out about her fiancee's alleged affair by reading it in a Sunday newspaper.

She told friends that when she phoned 32-year-old Law to confront him he blamed her for not being devoted enough to him, saying she was more interested in her career and was always too tired for him.

'Rather than feeling guilty and contrite he has turned the whole thing against Sienna,' said one. 'He said if she is not partying she is sleeping and he completely blames her for what he has done. 'He told her, "I told you I was unhappy. I told you I needed you to be there for me. Why didn't you listen to me?" '

Miss Miller's reaction was that Law can 'go to hell'. She retreated yesterday to her mother Jo's home in the capital.

Law, who was married for seven years to actress Sadie Frost and had three children with her, met Miss Miller two years ago on the set of the film Alfie. They became engaged on Christmas Day.

Miss Frost remains in charge of selecting the nannies for the children and a year ago employed 26-yearold Daisy Wright to look after them at weekends.

Miss Wright told the Sunday Mirror that she slept with Law in March, after taking one of his children to see him in New Orleans, where he was filming All The King's Men with Kate Winslet. The other two children were holidaying in Spain with their mother. She said she and Law were drinking together and he complained that he did not have a girlfriend who was constantly by his side.

'I said to Jude I didn't understand why he didn't find a wife who didn't want a career and to party all the time,' she said.

'He said it is very hard to find a woman who wants this and he would love that more than anything.'

As Law stood up to leave he leant over her and said: 'If you are lonely come and see me.' And within seconds they were kissing.

Miss Wright told the newspaper the pair ended up in Law's bed. But after deciding to spend the night together they were discovered by one of his children.

'Jude woke up and the child said, "Daddy, Daddy, I'm having a bad dream'',' she said. Law told his child: 'It's all right, darling, go back to bed.'

Despite their affair being discovered, Miss Wright - who was often mistaken for Miss Miller while she accompanied Law on set - claimed they went on to sleep with each other four more times.

But she was sacked when the child told Miss Frost about having seen her in bed with Law.