Tonga - home of the Royalist's favourite Pacific monarchy - is holding a national holiday today to celebrate the lavish wedding of  27-year-old prince Tupouto’a ’Ukukalala, first in line to the throne, to his 25-year-old second cousin, Sinaitakala Fakafanua, who is 26th in line.

The celebrations coincided with the end of a 100-day mourning period following the sudden death in March of King Tupou.

But the marriage — the first of a crown prince in 65 years – has been criticised for continuing the practice of royal marriages occurring only between cousins, once thought to keep the bloodline strong, but now feared to create health problems related to consanguity, reports the Daily Telegraph.

A leader of the  Tongan community in New Zealand, Will Ilolahia, said many in Tonga opposed this week’s marriage but were reluctant to speak out.

“In the Tongan society we don’t have a word for cousins, cousins are actually brothers and sisters,” he told ABC Radio.

Mr Ilolahia said he was concerned about the genetic risk of close relatives marrying.