WHEN 50 Cent, the world’s biggest rap star, checks in to the five-star May Fair hotel in London’s West End this week he is likely to discover his bill has been cut by at least 50%.

Luxury hotels have stolen a trick from the fashion industry - which gives free clothes to singers and actors - and are cutting rates to celebrities in return for their endorsement.

The glitzy May Fair has struck deals with stars such as Paris Hilton, X Factor’s Louis Walsh, the singer Ronan Keating and members of the group Girls Aloud to give them the pick of its 410 rooms for as little as £100 a night. The penthouse suite, with a revolving bed and 100ft balcony, normally costs £2,000-£3,000 a night. The stars can get it for a fraction of that.

The Mandarin Oriental in Knightsbridge has an “ambassadorial” rate for celebrities and last year appointed Mary Mc-Cartney, daughter of Sir Paul, as its official photographer.

Show business agencies are competing to book celebrities into the May Fair and other hotels in the hope they will be spotted by paparazzi photographers loitering outside.

In return for the warm welcomes and lower rates, the hotels expect the celebrities to hold press conferences in their suites and mention where they are staying in interviews.

Hilton and Walsh both gave effusive interviews to the May Fair’s own television channel that have been posted on YouTube. Hilton, staying in the penthouse, said: “I love the suite. It’s beautiful.”

Such is the appetite for attracting a big-name clientele that some hotels are being accused of poaching guests, a practice introduced from New York where it is known as “elite napping”. Another London hotel is said to have offered a Hollywood star a free two-week holiday for himself and his family if he stayed with it.

Paul Stacey, founder of Formula 13, an agency that boasts “celebrities for any occasion”, said: “I have contracts with a number of leading hotels. We are very good at placing celebrities at hotels like the May Fair. Some do get special rates.”

Another celebrity booker said: “I was asked by the management of hip-hop singer Missy Elliott to find her accommodation. After one call I found myself being whisked around like royalty. Superb rooms were offered at knockdown prices.”

Critics of the deals claim noncelebrity guests have to subsidise the pop stars through higher bills. Furthermore, in contrast to the cut-price luxury for celebrities, a whistleblower at the May Fair said staff had to pay fines for errors. Hotel documents show six staff on reception were “fined” £150 when a guest was mistakenly given back a £900 deposit he had paid in July.

The source said: “The May Fair is only interested in image and attracting celebrities. Staff are treated as inferior.”

She added: “It is easy for a receptionist to be blamed for a mistake and pay the price.”

The May Fair said: “We have a close relationship with people like Paris Hilton, Louis Walsh, Ronan Keating, Nicola Roberts and Sarah Harding of Girls Aloud and others and they do enjoy special rates. This is something the fashion industry has always done. It is a mutually beneficial relationship. We would never exploit any celebrity.”

It added: “Staff who are docked pay sign an agreement that they have broken procedures either knowingly or accidentally. It is part of their contract. A member of staff who let a guest who said he had run out of money and would reimburse us later leave without taking any credit card details or contact details from him was asked to reimburse the money because she had broken all protocols. This is standard practice in the hotel industry."

The Mandarin Oriental said: “We have a strict privacy policy and cannot say anything about our celebrity guests, but celebrities who regularly stay at the hotels enjoy a bartering agreement.”

A 50 Cent spokesman said: “50 Cent is coming in to do some filming. He always stays at the May Fair because he gets a special deal there.”