Thai oarsmen row during the first full dress rehearsal for the Royal barge ceremony along the Chao Phraya river in Bangkok

Thailand's newly crowned king has postponed next week's final event marking his historic coronation -- a royal barge procession down Bangkok's Chao Phraya river -- by almost two months, a deputy premier announced Thursday.

The 52-barge procession was scheduled for October 24, and on Thursday Thai oarsmen donning hats and gold-flecked attires rowed down the Chao Phraya river for the first full-dress rehearsal.

But deputy prime minister Wissanu Krea-ngam later told reporters the procession has been moved to mid-December due to worries over the "water conditions and weather".

"After 10 small rehearsals and a final rehearsal today, we realised the procession would not maintain the traditional formation and beauty and the event should wait," he said.

"The king has decided to postpone it to December 12.".

The elaborate ceremony is the final phase of the coronation of King Maha Vajiralongkorn, who will travel on a barge downriver -- allowing Thais a rare chance to greet the monarch and his queen.

The procession originated from the river journeys of ancient Thai kings as they lead their battle flotillas into war.

The Royal Household Bureau also announced late Thursday that the king's sister, Princess Sirindhorn, was admitted to hospital for an infection in her large intestine.

Vajiralongkorn is the tenth monarch of the Chakri dynastry, which has reigned over the kingdom since 1782.

While he ascended the throne three years ago following the death of his beloved father, Vajiralongkorn's official coronation was only held in May in an elaborate three-day affair.