King Bhumibol Adulyadej was so revered that many Thai people around the country fainted or felt unwell when they learnt this week that he had died after 70 years on the throne.

A mourner is attended to after passing out while waiting for the motorcade carrying the body of King Bhumibol Adulyadej outside the Grand Palace in Bangkok, Thailand October 14, 2016.

Two days on, the government says it has provided medical treatment to scores of people overcome by grief and has told mourners they can call a hotline to help them through the trauma.

"There are people who hyperventilate and we try to calm them down by talking to them," Boonruang Triruangworawat, director general of the Department of Mental Health told Reuters on Saturday. "Others we have to send to hospital."

He was speaking outside the Grand Palace, a glittering complex of halls, pavilions and gardens where the remains of the king will lie for months before a royal cremation.

Thousands of black-clad mourners gathered there on Saturday, some holding umbrellas against the sun, and others fanning themselves, visibly overcome with grief.

Dotted around the riverside palace were dozens of ambulances and medical tents. Teams handed out cotton wool soaked in ammonia solution to help revive people close to fainting, said a Reuters reporter at the scene.

Boonruang said around 200 people had been treated by medics since the king died, some for hyperventilation due to anxiety.

Thais loved King Bhumibol as a father figure, and the death of the world's longest-reigning monarch after 70 years on the throne has left many uncertain about the future.

One of those being treated at the palace, Suchin Yamatad, 64, said he felt dizzy at the news of the king's death.

"It's just that I'm old. I've seen His Majesty for a long time," he added.

There was a government web page to advise people how to cope with grief, besides a counseling hotline, the Ministry of Public Health said.

"Those who are overcome with emotion can call it," said ministry spokesman Suwannachai Wattanayingcharoenchai.

Most of Thailand is hushed in dignified mourning, but in some areas news of the death fueled tension.

About 400 people gathered outside the home of a soya milk vendor in the southern province of Phuket on Friday to protest against a Facebook post by the vendor's son that they saw as insulting to the king, police said.

Some shouted threats.

"The messages aren't necessarily aggressive, but they hurt the feelings of Thai people who are grieving," said Teerapon Tipcharoen, the Phuket provincial police commander in charge of the case.

The vendor's son could be charged with breaking Thailand's royal defamation and computer crimes law, he added.

Thailand's strict lese-majeste laws protect the most senior royals from insult. A junta that took power after a May 2014 coup has used the law to hand down stiff sentences to critics of the monarchy.

Source: Reuters