The body of the Thai king's eldest daughter was brought to the royal palace in Bangkok on Saturday (Jun 13), as thousands of black-clad mourners lined the procession route.

Princess Bajrakitiyabha, known as Princess Bha, died aged 47 on Thursday following an abdominal infection.

She had already spent more than three years in a coma due to a cardiac condition.

"When it comes to saying goodbye, it's not easy for us," mourner Donnapha Kladbupha, a 54-year-old English teacher and self-described royalist, told AFP.

The monarchy represented "unity" for Thai people during times of distress, she said.

Others queued nearby for their turn to perform a Buddhist ritual of pouring holy water into a ceremonial bowl placed before a portrait of the princess.

"I'm sad that she passed away, especially when I saw her pictures as a child," another mourner, Nitikan Tephakham, 79, from the northeastern province of Roi Et, told AFP.

"When she was sick, I prayed for sacred beings to protect her and hoped for a miracle," she said.