Mr Singh was released on bail but no date was set for the trial
A Malaysian opposition leader has been charged with sedition for allegedly insulting a royal figure.
Karpal Singh pleaded innocent to the charge of insulting Sultan Azlan Shah of Perak state and was freed on bail.
His arrest came a day after his son, MP Gopind Singh Deo, was suspended from parliament for calling the deputy prime minister, Najib Razak, a murderer.
Mr Najib is expected to become prime minister in the next few weeks amid rising political tensions.
"Obviously it is politically motivated. There can be no doubt about that," said Mr Singh, chairman of the opposition Democratic Action Party (DAP).
He accused the government of using the Sedition Act "as a political weapon against its political opponents."
Under Malaysian law, any act that provokes hatred, contempt or disaffection against a state ruler is considered sedition.
The crime carries a maximum sentence of three years. A trial date has yet to be set.
The case comes amid a power tussle in Perak. Following elections in March 2008, the state was governed by a three-party opposition alliance that included the DAP.
But earlier this year, three Perak state legislators defected, tipping the balance in favour of the governing National Front coalition.
The Sultan of Perak fired the alliance's administration and asked the National Front to govern - a move that was questioned by Karpal Singh, and led to his arrest.
The opposition is campaigning for fresh state elections.
Meanwhile, the likely appointment of Najib Razak as prime minister has resurrected allegations of his involvement in a long-running scandal over the murder of a Mongolian woman.
Mr Singh's son was suspended from parliament for one year on Monday after he called Mr Najib a murderer, referring to the 2006 case of the death of Altantuya Shaariibuu.
The National Front has ruled Malaysia for more than 50 years.
But the opposition three-party alliance won an unprecedented five of Malaysia's 13 states in general elections last year, in a dramatic shift in the balance of power.