Malaysian police arrested the eldest daughter of jailed opposition leader Anwar Ibrahim for alleged sedition on Monday, a move slammed by critics as a crackdown on dissent.

Nurul Izzah Anwar, a lawmaker and a vice president of her father’s People’s Justice Party, was to be detained overnight because of a speech she made last week in Parliament, said Fahmi Fadzil, the party’s communications director.

Police did not specify which part of the speech — which questioned Anwar’s jailing — was seditious, and told Nurul Izzah’s family that the detention was to facilitate investigations, Fahmi said.

Fahmi said the arrest was “ridiculous and outrageous,” noting that lawmakers have immunity over comments made in Parliament. He said the move was intended to silence the opposition after Anwar was jailed for five years last month, when he lost a final appeal against a sodomy conviction.