By Guy De Launey
BBC, Phnom Penh
There is an air of confusion in Cambodia at the moment.
Since New Year's Eve, three prominent human rights activists have been arrested and jailed pending trial for defaming the government.
UN envoy Yash Gai hopes to persuade Cambodia that rights matter
They have joined two others facing similar charges.
Several activists and government critics have left the country rather than risk arrest. The leader of the main opposition party is in self-imposed exile - and has recently been sentenced to 18 months in prison for defaming the leaders of the governing coalition.
Human rights groups and diplomats alike say they are increasingly worried about the situation.
The United Nations Special Representative to Cambodia on Human Rights, Yash Ghai, believes it is time for the world to worry about the direction Cambodia is taking.
"The people of Cambodia are deeply committed to human rights precisely because they have suffered so much from the denial of those rights," he said.
The opposition is in disarray without its leader Sam Rainsy
"The government here seems to think that human rights are a nuisance. They identify opposition groups with human rights. I am hoping that in my time here I can persuade the government of the value of human rights"
The government has had an adversarial relationship with Kem Sokha since he founded the Cambodian Centre for Human Rights three years ago. But the events of New Year's Eve marked a serious escalation of that conflict.
The rights worker was arrested and charged with defaming the government because of a banner displayed at a rally to mark International Human Rights Day in December.
The banner accused the government of selling land to Vietnam, following the ratification of borders between Cambodia and Vietnam which were originally set during the Vietnam-backed regime of the 1980s, and which some people feel lost Cambodia land.
One of the rally's organisers received similar treatment, and a few days later one of Kem Sokha's colleagues was also arrested and charged.
It was the second round of arrests of government critics in recent months. In October, the government brought charges of defamation and incitement against seven people who also criticised the proposed border treaty.
Five of them left the country before they could be arrested, and other critics of the government also fled as rumours swirled around Phnom Penh.
Defamation is a criminal offence in Cambodia, a legacy of the United Nations transitional regime in the early 1990s. Critics say it was a law for exceptional circumstances that should have been replaced by now.
The government, however, has defended its right to prosecute those whom it says have broken the law. The chairman of the government's Human Rights Committee, Om Yen Tieng, insists the government is tolerant of criticism, but not when it amounts to defamation.
"We never jail any of the guys who criticise the government. They're still free. We put in jail people who abuse the law," he said. Some NGO workers say the government has become increasingly intolerant to criticism over the past year. International attention has largely been focused on areas such as Afghanistan and Iraq, and the West sees Cambodia as an ally in its efforts to combat terrorism.
At the same time, China has become the biggest investor in Cambodia, and asks few questions about human rights issues. That means that the words of Western diplomats may carry less weight.
The United States ambassador, Joseph Mussomeli, warned that the debate on the border issue was "a real test of Cambodia's commitment to democracy, and it seems they are failing".
Mr Mussomeli promised to "speak out - and speak quietly to the government."
But Cambodia's politicians are well aware that Western countries are reluctant to add conditions to the hundreds of millions of dollars in aid they provide every year.
The human rights campaigners who have so far escaped jail or arrest warrants are exasperated. They have heard both the government and donors argue that Cambodia needs time to establish a truly democratic system with freedom of speech.
"Thirteen years is quite a long time to make some progress," said Kek Galabru, president of the local human rights group Licadho. "We advance some steps, we go back. It's like a dance, a cha-cha-cha. I'm so sorry about that."
The government may well be operating within the law. But using criminal charges against people who speak out is giving a poor impression to international donors and investors alike.
They want to know whether recent events are just a speed-bump on Cambodia's road to democracy and development - or the start of something more worrying.