Malaysian authorities are carrying out the broadest crackdown on the political opposition and social activists since the era of strongman leader Mahathir Mohamad, as traditionalists in the long-ruling ethnic Malay party appear to gain the upper hand.
The setback for civil liberties in the multi-ethnic former British colony, which had appeared set on a path of greater openness just two years ago, comes as democracy retreats across mainland Southeast Asia following a military coup in Thailand and fading reform hopes in Myanmar and Cambodia.
Susan Loone, a reporter at online news site Malaysiakini, which is critical of the government, was the latest to be detained by police on Thursday under the colonial-era Sedition Act, days after a law professor was charged over comments in an online news article on a 2009 political crisis.
Prosecutors have charged four people with sedition in the past two weeks, including the professor, with new police investigations against opposition figures or activists being announced frequently.
This year, seven opposition politicians, six of them members of parliament, have been charged with crimes, including sedition, for things they have said. Another has been convicted.
The opposition's de facto leader, Anwar Ibrahim, was convicted and sentenced to jail in March on a sodomy charge that rights groups say was politically motivated.
The three-party opposition, which has eroded the ruling coalition's majority in two straight elections, says the 1948 Sedition Act is being employed selectively against its members, allies and social activists to undermine the alliance.
The sedition law criminalizes speech with an undefined "seditious tendency".
Phil Robertson, Asia deputy director of Human Rights Watch, said the prosecutions were reminiscent of so-called Operation Lalang in 1987 under Mahathir, when more than 100 opposition politicians and activists were arrested under an old Internal Security Act (ISA) which allowed detention without trial.
"The parameters are basically the same - you are using an antiquated draconian law to go after the opposition," he said.
The reason for the crackdown is unclear, but pressure has been building on Prime Minister Najib Razak from conservatives in his ruling United Malays National Party (UMNO) to take a tougher line against opponents.
The charismatic Mahathir, who led Malaysia for 22 years until 2003 and remains an influential conservative force, announced two weeks ago he was withdrawing support for Najib.
In a savagely critical blog post, he said Najib's policies had "destroyed interracial ties" and led to an increase in crime in general.
"Mahathir accused Najib of being weak. I think this is a very strong signal Najib is trying to send to say that 'I am not weak'," said Ong Kian Ming, an opposition member of parliament.
Mahathir, a defender of majority ethnic Malay rights over minority ethnic Chinese and Indians, used tough security laws to stifle dissent and has lamented Najib's repeal of the Internal Security Act.
Najib, a self-described moderate whose reformist plans were dealt a setback by a weak election performance last year, pledged in 2012 to repeal the Sedition Act and says he intends to replace it with a new law by the end of next year.
But many senior UMNO leaders are opposed to that and also want him to restore the ISA.
The Prime Minister's Office did not respond to requests for comment on the prosecutions or on comparisons to the Mahathir era. In a statement on Aug. 30, a government spokesman said sedition cases had to be tried under existing laws until new legislation was ready, and were a "matter for the courts".
Sources close to Najib say he retains his reformist drive, but is fighting a rearguard action against the conservatives.
Shahidan Kassim, a minister in the Prime Minister's Department, was quoted by media on Friday as saying the government had only pledged to review the Sedition Act, not abolish it. Najib has said he is committed to repealing it.
"Not everyone around the PM is on the same page with him," said Saifuddin Abdullah, an UMNO moderate and former deputy minister. "I hope this is not a move to fail the prime minister in many of the things he is trying to do."
Supporters of the sedition law say it is needed to clamp down on inflammatory actions that could stir up ethnic or religious tension in the diverse nation of 29 million.
But although some people aligned with UMNO or Malay rights groups have been charged under the law, it is used far more often against anti-government activists or the opposition.
N. Surendran, a lawyer and opposition member of parliament, was charged with sedition last month for saying that the verdict in Anwar's trial was "flawed, defensive, and insupportable", a view shared by various international human rights groups.
Loone, the journalist, was arrested and later released on bail after Malay rights groups lodged a police report about an article she wrote quoting an arrested opposition politician saying he was treated like "a criminal" in police custody.
The opposition Pakatan Rakyat coalition says electoral calculations may be behind the arrests, which would result in by-elections if the legislators who are suspects are found guilty.
"What we are seeing is thus a blatant and shameless attempt by Najib to hijack democracy by having duly elected lawmakers from Pakatan to be stripped of their democratic entitlements and disqualified from contesting in the subsequent by-elections," Anwar, who is free pending an appeal, said in a statement.