Another blogger, Raja Petra Kamaruddin, was detained last week
An opposition blogger has been arrested for allegedly displaying a national flag upside down on his website, as the government comes under more pressure.
Syed Azidi Syed Aziz, better known as Kickdefella, is the second blogger to be arrested in a week.
The Malaysian opposition leader, Anwar Ibrahim, is demanding a vote of no confidence in the government.
Mr Anwar says he now has the support of enough MPs to bring down Prime Minister Abdullah Badawi.
Mr Syed Aziz, picked up late on Wednesday, is being held under the Sedition Act.
He is known as a supporter of the conservative Islamic PAS party, a component in the coalition seeking to topple the government of Prime Minister Abdullah Badawi.
Mr Syed Aziz's website had recently advocated that people fly the Malaysian flag upside down as a protest against the current political upheaval.
Mr Abdullah reportedly called the protest "a malicious act" and police were told to investigate the campaign.
"We were informed that the police were looking for us on Tuesday and waited for them but they didn't show up," his Mr Sayed Aziz's wife Bariah Ishak told the Star daily newspaper.
"We thought the worst was over but they came looking for him and so he surrendered," she added.
Mr Abdullah's government is under pressure from an emboldened opposition, which is trying to persuade members of parliament to defect in favour of Anwar Ibrahim's Pakatan Rakyat alliance.
Mr Anwar says he has written to the prime minister demanding a special session of parliament no later than Tuesday.
"Any delay in his response would be interpreted as nothing short of sabotage of democratic process and abuse of executive powers. It is therefore critical for the prime minister to respond," he told reporters.
Mr Abdullah has rejected Mr Anwar's claims of majority support in parliament. In response, Mr Anwar said on Thursday that the way to find out was to "go to the parliament".
Mr Anwar needs 30 MPs to cross the floor to join its 82-strong bloc and seize a majority in the 222-member assembly.
Mr Anwar challenged the government to put itself to the test in parliament
On Wednesday, one small party pulled out of the governing coalition and Mr Abdullah hinted that he might step down early.
He also announced he would be handing the finance portfolio to his deputy, in return for taking the defence portfolio.
The parliament is currently in recess.
The ruling Barisan Nasional, or National Front, has been in power since Malaysia gained independence from Britain 51 years ago.
It lost its two thirds majority in parliament for the first time in elections in March.
Discontent has been rising as the economy falters and racial tensions have flared between the country's dominant Malays and the large minorities of Chinese and Indians.
The latest arrest follows that of the well-known blogger, Raja Petra Kamaruddin on Friday under the country's Internal Security Act, which allows for detention without trial.
He had attacked government figures on his website, called Malaysia Today, and was charged with sedition and defamation for alleging that Deputy Prime Minister Najib Razak and his wife were linked to the sensational murder of a Mongolian woman.
Opposition Democratic Action Party politician Teresa Kok was arrested at the same time, apparently for objecting to a mosque broadcasting its prayers too loudly.
A reporter, Tan Hoon Cheng, from the Chinese language daily Sin Chew was also arrested on the weekend but was released after a day.
Rights groups have protested against what they say is a government crackdown on dissent and repression of constitutional freedoms of speech.
They say about 63 people are being held under the ISA.
The government minister responsible for legal affairs, Zaid Ibrahim, resigned earlier this week in protest at the government's resort to the harsh law.