Susan Barrantes was buried next to her late husband Hector in a vault below her house, next to a polo field on the Argentinian estate.

The local parish priest conducted the 30 minute service in front of a small group of mourners.

Argentine President Carlos Menem sent a floral tribute.

The Duke of York did not travel to Argentina for the funeral. He stayed in Balmoral carrying out private engagements.

Floral tribute from Carlos Menem

Princesses Beatrice and Eugenie were at their Sunninghill home in Berkshire, being looked after by their nanny.

The Duchess's sister Jane arrived late on Monday from her home in Sydney, Australia.

A spokeswoman for the Duchess said: "There will be a memorial service for Mrs Barrantes in Buenos Aires on Thursday night or Friday morning.

"There will be a service of thanksgiving for her life in England towards the end of the year."

Previous accident

Susan Barrantes was killed in a car crash on Saturday.

According to Argentinian newspaper reports, the Rover 420 she was driving was travelling at 124mph when it crashed into a Renault Trafic van.

Duchess' daughters: stayed at home

El Tribuno reported that police investigators had found the speedometer of the car stuck at 200kph.

It also emerged that Mrs Barrantes, who was 61, had been involved in another serious road accident a year before the fatal crash.

On that occasion her life was saved by her seat belt as her car overturned up to seven times.

A friend of Mrs Barrantes, German Sanchez, 24, told an Argentinian newspaper: "She drove very well but she used to really step on the accelerator - she regularly went at 150 or 160kmp (93 to 99mph)."

Raphael Barrantes, Mrs Barrantes' 25-year-old nephew, survived Saturday's crash with minor injuries and left hospital on Sunday.

The driver of the Renault van was named as salesman Jose Maria Rodriguez, 60, of Tres Lomas - reported to be a close friend of Mrs Barrantes.

He remains in hospital with a broken right foot.