Najib Razak, Malaysia's new prime minister, had led the government's move to takeover the Perak assembly, persuading politicians to join the ruling coalition and so overturning the opposition majority in the assembly.
In a separate development following Wong's arrest, three opposition supporters were arrested on Wednesday after they tried to deliver a cake to Najib to mark the birthday of a Mongolian woman murdered in 2006.
Two police officers were convicted and sentenced to hang for the murder last month, but there have been repeated rumours that Najib may have been connected to the case – allegations he has denied.
|Najib came to power in April vowing to
"uphold civil liberties" [AFP]
The spate of arrests have raised concerns among opposition leaders of a crackdown by Najib against critics of his government.
Najib, who took office on April 3, came to power promising to "uphold civil liberties" and demonstrate "regard for the fundamental rights of the people of Malaysia".
"Despite the rhetoric of tolerance by the new PM Najib, he's bent on using tough, draconian measures," Anwar Ibrahim, Malaysia's opposition leader, told Reuters news agency.
"That the campaign for people to wear black can be deemed as seditious and a threat to national security, this is ridiculous."
Anwar, a former deputy prime minister is to stand trial in July for sodomy, charges he says are politically motivated.
The former deputy prime minister-turned opposition figurehead was imprisoned on corruption and sodomy charges in the late 1990s, although the sodomy conviction was later overturned.