The public has been invited to join in Saturday's mass chanting of a new version of the Royal Anthem dedicated to the memory of His Majesty King Bhumibol Adulyadej.
The mass singing will be taped for showing later on television and at cinemas nationwide.
The taping will start at 1pm Saturday on Thanon Na Phra Lan Road outside the Grand Palace and at Sanam Luang, according to government spokesman Sansern Kaewkamnerd.
The event was thought up by national artist and renowned filmmaker and director MC Chatrichalerm Yukol, widely known as Than Mui, Lt Gen Sansern said.
The recording of the mass singing of the Royal Anthem will stand as a testament to the love between the Thai people and their King, he said.
The music will be played by the Siam Philharmonic Orchestra under the baton of Somtow Sucharitkul, featuring over a hundred instruments and another hundred chorus singers.
Lt Gen Sansern said that those who want to take part in the event are requested to gather at Sanam Luang by 10am for a brief rehearsal. They are also requested to wear black and bring along a candle each.
Pol Maj Gen Jirapat Phumjit, acting deputy commissioner of the Metropolitan Police Bureau, said that the mass singing event is expected to draw huge crowds, particularly during the three-day holiday period from Saturday to Monday.
Numerous people from the provinces are expected to travel to Bangkok to express their condolences over the passing of His Majesty the King at the Grand Palace, Pol Maj Gen Jirapat said.
Meanwhile, almost 40,000 soldiers have been deployed in the vicinity of the Grand Palace to assist and ensure the safety of mourners of the late King Bhumibol.
They are from 50 companies of the 1st Division and King's Guard, with another 150 companies taking turns to work in Sanam Luang and outside the Grand Palace, military sources said.
Lt Gen Apirat Kongsompong, the 1st Army commander, added that three of his deputies have been given the responsibilities of handling intelligence matters, public security and services, and traffic management in the area.
Maj Gen Thammanoon Withee, deputy chief of the 1st Army, said a joint peace-keeping command will play a coordinating role in working with the private sector and volunteers to assist people.
He said between 30,000-35,000 people have been visiting to sign books of condolences at the Grand Palace every day.
Soldiers will handle the queues when the public is allowed to pay homage before the body of His Majesty from Oct 28 onwards. The body of His Majesty the King is lying in state in the Dusit Maha Prasat Throne Hall inside the Grand Palace.
The 1st Army has also arranged accommodation at 15 locations for people from other provinces.
The public should be confident of their safety as soldiers have been on duty there around the clock. Metropolitan police, city officials and other soldiers deployed by the National Council for Peace and Order were also on duty there, said Maj Gen Thammanoon.
Thanongsak Pongprasert, deputy governor of the State Railway of Thailand, said the SRT has arranged more free long-haul trains for people in the provinces who plan to come and pay their respects to the late King in Bangkok during the long holiday.
The train services will start at Khon Kaen, Surin and Phitsanulok, and passengers can board the trains at stations along the way, Mr Thanongsak said.
Regarding medical assistance for people, deputy City Clerk Wantanee Watana said the city's Erawan Emergency Medical Centre will work with the Public Health Ministry and their allied medical units to provide first aid support at 11 spots around Sanam Luang.
Many people were found to have fainted at Sanam Luang due to low blood sugar levels, she said.
Ms Wantanee also said she was concerned about food being distributed to mourners because in the heat it would likely go off. Those who want to provide food to the public should contact a government joint operation centre to organise food handouts properly.
Wijarn Simachaya, director-general of the Pollution Control Department, said the agency will work with the Bangkok Metropolitan Administration and Thammasat University to support efforts to collect and sort rubbish in Sanam Luang and around the Grand Palace.
Lt Gen Sansern added that the weekly prime minister's TV programme on Friday would focus on government work that has perpetuated the King's initiatives, such as those concerning the economy.
