BANGKOK - SOMBRE Thais donned black clothes on Friday as the start of a six-day funeral ritual for the sister of the country's revered king cast a pall over the self-proclaimed Land of Smiles.

Princess Galyani, the elder sister of King Bhumibol Adulaydej, died on January 2. After a short initial ceremony on Friday, the cremation itself takes place on Saturday and other rituals will last until Wednesday.

It is the first full royal funeral in Thailand since 1996, a potentially unifying moment at a time of deep political strife and anti-government protests in the Buddhist kingdom.

'I want to express my loyalty to her and the monarchy and I do it with my heart. I am appreciate that most Thais are wearing black today to mourn her', said Mr Watchara Somsean, 39, a black-clad food vendor in Bangkok.

Bangkok's normally vibrant streets were muted on Friday, with most people on the futuristic Skytrain system wearing black shirts or jackets, while flags flew at half mast for the princess.

The government has asked television and radio stations to keep programming 'appropriate' while all Thais have been asked to wear black for the first three days of the ceremony.

'If someone passes away you should wear black or white but we prefer black ... because white to many means wedding', an official from the Government Public Relations Department told AFP.

At least 1.5 million people have paid their respects to Princess Galyani's embalmed remains, which have lain in state at the Grand Palace's Dusit Maha Prasat Throne Hall since her death from cancer, the Royal Household Bureau said.

The 10-month period between her death and the funeral was to make preparations for the building of the huge gilded crematorium and for the procession that will take her remains there.

An official 15-day mourning period followed Princess Galyani's death in January, although royal palace employees stayed in mourning 100 days after her death.

'I am Thai and must show respect to her. It's also our tradition', said government official Kachorchan Kakhao, 51. 'I feel grateful to see Thais are wearing black everywhere - in the bus, traders'. -- AFP