Princess Bajrakitiyabha, widely known as Princess Bha, passed away on Thursday at the age of 47 after suffering from 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.