Malaysian police have raided the office of electoral reform group Bersih and detained two officials on the eve of a street rally by the group seeking the resignation of Prime Minister Najib Razak over a financial scandal.

Bersih activists have vowed to proceed with Saturday's rally in Kuala Lumpur despite a police ban and fears of clashes with a pro-government group.

Bersih says on Twitter that its chairwoman Maria Chin and another official have been taken by police. It said Friday that police also confiscated 10 laptops, payrolls and bank statements.

Najib has kept an iron grip since graft allegations emerged two years ago in the indebted 1MDB state fund that he founded. 1MDB is at the center of investigations in the U.S. and several other countries.