Swaziland's royal family have long kept their distance from the paparazzi in a way British royals can only dream about. Not any more, thanks to the rise of Swazi Leaks, an online group determined to expose the opulent lifestyle of Africa's last absolute monarch.

The movement, inspired by Julian Assange's WikiLeaks, frequently publishes pictures of King Mswati and his family living the high life. One recent post says: "Our taxes pay for the king's children to party in Los Angeles in the USA, will we struggle to eat here in Swaziland."

The intimacy of the photos suggest someone in the king's inner circle may be leaking information about his movements.

All of which must come as a shock to Mswati, who rules Swaziland with an iron fist: opposition parties are banned, protests are swiftly crushed and a magazine editor and human rights lawyer were recently jailed.

The king owns a private jet, fleet of luxury cars and has a fortune estimated at about $100m (£60m). Meanwhile, about 60% of the population live on less than $1 a day.

In a rare interview this week the unknown activists behind Swazi Leaks discussed their motivations. "We wanted to try and expose some of the exploitation and corruption of the rich and powerful," they told Agence France-Presse.

"We get information and pictures from people who know or work for them. We have never told anyone what we do and try and not put anyone in jeopardy due to the information we have."

Swazi Leaks launched on Twitter last year and operates a Facebook page. One recent post reports how government officials splashed out for a person to leap out of the king's birthday cake. Another shows members of the royal family relaxing in the luxury Windsor suite at Heathrow airport.

The Swazi Leaks members refused to tell AFP their names or location in the southern African nation, which has a population of 1.2 million. They said: "Swaziland is a small country and there are a lot of rumours and half-truths with very little to back them up. We try and not tweet information that we feel has no basis.

"The message that royalty and their friends live off us, the people, like parasites will spread and be supported by evidence and not rumour. In this we hope that people will start demanding what is due to them."

They added: "Many, many Swazis think that their lives are the way they are due to forces beyond their control and that the king has their best interests at heart. We hope to show them that this is not necessarily true."

The group is aware that the authorities are watching, they told AFP. "We are followed by many Swazi journalists and even a few politicians and people within the royal sphere, which amused us. There are some people who seem angry with what we're doing – you can see the exchanges on our tweet history."

"Though they don't seem to actually live in the country and seemingly come from privileged backgrounds, so we can understand that what we share is uncomfortable for them."

They also said that WikiLeaks was a major inspiration because some of the diplomatic cables it released discussed Swaziland. "They showed some of the alliances the ruling elite had with Gaddafi and other dictators, which allowed some Swazis to see inside the ivory tower that is the monarchy."

Many Swazis in rural areas, where the king remains popular, do not have internet access, so Swazi Leaks' impact is likely to be limited. But it was welcomed by Muzi Masuku, Swaziland programme manager of the Open Society Initiative. "The dynamics of social media are quite enormous," he said. "We no longer have to rely on a media so tightly controlled. This has been a great help in knowing what's going on and dispelling some of the myths."

He added: "Whoever is doing this has access to a good cache of pictures. It has to be someone who's close enough but able to hide his identity."

Not all the king's excesses are being captured, however. Masuku lamented: "He went to Disneyland. The pictures of him meeting Mickey Mouse and gambling in Las Vegas would have been useful."