The socialite Paris Hilton - who demanded to be saved from 45 days in jail because she provides "beauty and excitement to most of our otherwise mundane lives" - is set to escape serving most of her term anyway because of prison overcrowding, it emerged today.

The Los Angeles sheriff's department has announced that the heiress to the Hilton Hotel fortune could serve as little as 21 days because the county's prisons are "bursting at the seams".

Today's developments came as the model, known for her hard partying, claimed to have followed up an bizarre earlier pardon demand to Arnold Schwarzenegger, the governor of California, with a letter to President Bush, in which she urged him to set aside her jail sentence "for the sake of all the poor, less fortunate people in our country".

However Steve Whitmore, a spokesman for the sheriff's department, told the Los Angeles Times newspaper that she was likely to get away without doing most of her sentence anyway.

"It’s possible that it could be 21 days, 23 days. It’s a complicated formula that the state sets down. It’s possible that she could do less time," he said.

The spokesman added that the city's main prisons were "bursting at the seams," which sometimes meant that minor female sentences were not fulfilled.

"Some women inmates have been released after serving only 10 per cent of their sentence," he said.

"'Lost' actress Michelle Rodriguez was sentenced to 60 days in jail for violating probation after her drunken driving arrest in Hawaii. She was released in hours because of overcrowding."

Mr Whitmore stressed, however, that she would not receive any special favours because of her celebrity status. "She’s going to be treated like any other low-level security risk," he said.

Hilton, 26, was sentenced to jail last week for violating the terms of her probation in an alcohol-related reckless driving case. A judge ordered her to report to the women’s prison in Lynwood, California, by June 5.

After sentencing, the socialite - who attracted worldwide attention when a sex tape she made with her boyfriend was released on the internet - proceeded to make a bizarre appeal to Mr Schwarzenegger to be spared prison, after her friend started a petition.

The petition said: "She provides hope for young people all over the U.S. and the world. She provides beauty and excitement to (most of) our otherwise mundane lives."

Acknowledging the campaign, she later wrote on her blog: "My friend Joshua started this petition, please help and sihn (sic) it. i LOVE YOU ALL!!!!!"

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