The coronavirus pandemic has led to a rare surge of online posts in Thailand questioning King Maha Vajiralongkorn and the monarchy.

On Sunday a government minister subsequently warned that inappropriate posts could lead to jail.

Insulting the monarchy is a crime, punishable by up to 15 years in prison.

Thailand has been a constitutional monarchy since a 1932 revolution ended absolute royal rule, but the monarchy remains a central part of traditional Thai culture. Some Thais consider the king to be semi-divine.

Thailand's King Maha Vajiralongkorn (R) and Queen Suthida during their wedding ceremony in Bangkok in May last year.

Thailand's King Maha Vajiralongkorn, pictured being carried on the royal royal palanquin by royal bearers during the Royal Procession outside the Grand Palace in Bangkok

King Maha Vajiralongkorn, shown here being greeted by crowds along with Queen Suthida on the final day of his coronation, was crowned in May 2019

However, a Thai-language hashtag that translates to #whydoweneedaking? was one of the top trending topics on Twitter in Thailand after an overseas Thai activist posted about King Vajiralongkorn continuing to travel in Germany during the coronavirus crisis.

Thailand confirmed its first and only death from Covid-19 on March 1. The country has had 721 cases since the outbreak.

King Vajiralongkorn, 67, who was crowned last year, has a second home in Germany on Lake Starnberg, according to German news website Bild. He spends much of his time outside Thailand.

King Maha Vajiralongkorn pictured walking through a mall in Thailand. He has been the country's king since 2016

King Maha Vajiralongkorn is often seen travelling abroad, and is known to enjoy riding his bike around Germany and Swizerland. He is pictured here wearing a croptop in Swizerland.

King Maha Vajiralongkorn and former General Sineenat Wongvajirapakdi. Sineenat was Thailand's first royal consort in around a century, however the Thai king stripped her of all titles and military ranks for being 'disloyal' and conducting a rivalry with Queen Suthida the palace said in October

The King reportedly has a house in Germany near Lake Stamberg, which is also on lock-down during the coronavirus outbreak

The number of confirmed cases of coronavirus in Thailand has risen to 721, the second highest-number in Southeast Asia after Malaysia, according to official data announced by national health authorities. One person has died.

The hashtag questioning the monarchy was used more than 1.2 million times in 24 hours by Sunday, according to data on Twitter based on hashtags trending for users in Thailand.

Thailand's Royal Palace did not respond to requests for comment on the posts.

On Twitter, Minister of Digital Economy and Society Puttipong Punnakanta posted a warning to citizens against breaking laws on online content, accompanied by an image of a handcuffed hand above a keyboard

Thailand's Minister of Digital Economy and Society Puttipong Punnakanta posted a warning on Twitter to those using the hashtag that such actions can lead to jail time in the country

'I'd rather not comment,' he told Reuters when asked whether his March 22 post was related to those about the monarchy.

'I didn't specify what this was about - this is a general reminder. We follow all issues, like fake news,' he said. 'We are monitoring regularly as much as we can. We respect self-expression but if it causes damage, we will exercise the law.'

When asked whether the government would take action over the posts, government spokeswoman Narumon Pinyosinwat said the situation was being monitored, but any government action would depend on consultations with security agencies.

Among the first to use the hashtag was prominent Thai exile Somsak Jeamteerasakul, who posted on Saturday that the king was travelling in Germany while Thailand was dealing with the coronavirus outbreak. Investigating this, Reuters was unable to verify where the king had travelled during this period.

Andrew MacGregor Marshall, journalist and author of 'A Kingdom in Crisis: Thailand's Struggle for Democracy in the Twenty-First Century' tweeted images that appear to demonstrate King Vajiralongkorn growing unpopularity.

'Another interesting sign of King Vajiralongkorn’s worsening unpopularity in Thailand is the number of defaced banknotes in circulation,' wrote, while posting an image of a defaced bank note.

Marshall also shared a story that said King Vajiralongkorn had donated 100 ventilators to Thai hospitals, claiming that this was 'fake news'.

He said: 'The photo used in yesterday's fake news about King Vajiralongkorn donating 100 ventilators to Thai hospitals has been identified. It was taken in Italy and has nothing to do with Thailand.'

Open disparagement of the monarchy has been rare, but in the past year other Twitter criticism has included a #royalmotorcade hashtag about traffic jams caused by members of the royal family.

The king later ordered police to limit roadblocks for motorcades.

Thailand was the first country outside China to record a case of the virus in January, but reported only 42 infections before the start of March, according to statements from the Ministry of Public Health.

As cases have surged, more stringent control measures have been imposed. Those include requirements that anyone travelling from outside the country, including Thai citizens, needs special travel papers to fly to the country.

The tourist industry that accounted for more than a tenth of gross domestic product has suffered heavily.

Provincial authorities announced on Saturday that the capital Bangkok will close malls for 22 days although supermarkets will be allowed to remain open. Bars in the city will remain closed for that period, as will schools. Other Thai provinces are increasingly applying restrictions.