US First Lady Michelle Obama and her nine-year-old daughter Sasha have arrived on Spain's Mediterranean coast for a vacation with friends at a luxury hotel where they have booked 60 rooms.

The pair and their entourage arrived at the Hotel Villa Padierna in the hills above the resort town of Marbella, a haunt for the rich and famous, aboard a cavalcade of vehicles. They had flown to Malaga on a US air force plane.

President Barack Obama, who celebrates his 49th birthday on Wednesday, has stayed behind in the United States as did the couple's elder daughter, 12-year-old Malia, who is attending a summer camp.

The White House has described the four-day visit as "a private, mother-daughter trip with longtime family friends".

Michelle Obama was however scheduled to meet Spain's King Juan Carlos and Queen Sofia at their summer palace on the Balearic island of Majorca, a short flight from Marbella.

Spanish media reported the visit with the Spanish royals could come this weekend.

The US First Lady will visit the city of Granada, the former seat of Moorish rule in Spain which is located some 180 kilometres (110 miles) north of Marbella, on Thursday, a spokeswoman for the municipality told AFP.

She will take in the Alhambra fortress-palace, Spain's most-visited tourist attraction, as well the city's cathedral and the hilltop Albaicin quarter of narrow alleyways and small squares, the spokeswoman added.

Earlier on Wednesday the hotel's owner Ricardo Arranz told public radio RNE that the Obamas had reserved 60 rooms at the hotel for themselves, their friends and their extensive secret service detail.

"Everything is ready," he added.

In recent days local officials have had roads re-paved, gardens tidied up and new streets lights installed while the hotel has flown a US flag at its entrance in the Obama's honour.

Dozens of photographers and reporters have staked out the entrance to the five-star hotel, where rates for a room run from 250 euros for a room to 5,000 euros (6,500 dollars) for a villa with 24-hour butler service and private pool and garden.

An Italian palazzo-style building about five kilometres (three miles) from the coast, the hotel has five restaurants, a spa and access to three 18-hole golf courses.

In an interview published Tuesday in the daily Diario de Sevilla, Arranz said the Obama family had asked "for no special treatment. All that they have asked for is discretion."

"More than nervous, we feel a huge responsibility to ensure that all goes well because of the repercussions the visit is having, which could be good for this hotel and for all of the Costa del Sol," he added.

Spanish PR firm Oak Power Communication estimates the visit will generate about 50,000 reports on radio and television and in newspapers around the world and provide publicity for Spain's southwestern Andalucia region worth around 800 million euros (one billion dollars).

Marbella, where Arab royals maintain vast properties, lies on what the British press has dubbed the "Costa del Crime" because of the large number of fugitives reputedly hiding out there.

In 2006 it was rocked by a real estate corruption scandal that led to the dissolution of the town council.

The city is keen to turn the page on a reputation for sleaze which it gained in the 1990s with the election of mayor Jesus Gil, who transformed it into a glitzy resort through massive property speculation during his 15-year term.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.