Eswatini's prime minister has denied that King Mswati III has fled to South Africa following clashes between the security forces and demonstrators.

Pro-democracy protests intensified overnight in the country, formerly known as Swaziland, with government buildings, shops and trucks set alight.

The 53-year-old king, who came to the throne 35 years ago, rules by decree.

His critics accuse him, and his 15 wives, of leading a lavish lifestyle and treating opponents harshly.

His private plane was reported to have taken off from Eswatini, which is a landlocked country smaller than the US state of New Jersey, on Monday night.

But acting Prime Minister Themba Masuku appealed for calm in Africa's last absolute monarchy, saying such reports were untrue.

"Following the false media reports circulating, I would like to take this opportunity to assure the emaSwati and the international community that His Majesty King Mswati III is in the country and continues to lead in working with the government to advance the kingdom's goals," his statement said.

The private Swazi News paper has been tweeting some scenes of the unrest, showing buildings on fire in Matsapha, an industrial town which witnessed much of the violence.

Why are people protesting?

The trouble began in May after law student Thabani Nkomonye's body was found outside the city of Manzini.

Police said he was a victim of a car accident, but students alleged the police were involved in his death.

Demonstrations erupted in response, originally organised under the hashtag #JusticeforThabani - calling for an end to police brutality and have since morphed into calls for political change.

Things began to deteriorate over the weekend after the government banned protests - when people would gather to hand in petitions demanding change.

Crowds rallied with banners and chanting slogans calling for King Mswati to make way for democratic reform.

"True to form this government responds to people's grievances with the use of violence and force," Mlungisi Makhanya, leader of the opposition Pudemo party, told the BBC's Focus on Africa radio programme.

What reforms do they want?

According to Mr Makhanya, young people want political freedoms and jobs - in particular an elected prime minister with executive power.

Another key demand is an end to the royal family's extravagant spending as most Swazis with a job work in neighbouring South Africa and send their earnings home.

"They are demanding an end to royal supremacy so that a lot of national funds are not spent on feeding one family," he said

"It is unhealthy for any nation in the world to have powers that rest with one family at the expense of the entire nation."

Mr Makhanya says the country's infrastructure and basic services are collapsing, including the health service in a country with the world's highest prevalence rate for HIV/Aids.

"Our people are unnecessarily dying because ambulances can't access people because of the poor state of our roads," he added.

What is happening now?

According to the AFP news agency, soldiers were deployed overnight to Matsapha.

There are chaotic scenes in the capital, Mbabane, where a journalist told the BBC residents have been fleeing, with traffic jams leading out the city and cars queuing at petrol stations for fuel.

A shop assistant in Mbabane told the Reuters news agency: "I can hear gunshots and smell teargas. I do not know how I will get home, there is nothing in the bus rank, there is a strong presence of riot police and the army."

The army is also reported to have deployed there and businesses and schools are shut.

Some tweeters are reporting that the MTN Eswatini mobile phone network is no longer working.

It has also been reported that the arrest has been ordered for two MPs who have been at the forefront of calls for democratic change.