PKR secretary-general Rafizi Ramli has been detained by the police as he exited the Parliament building gates this evening.
Inspector-general of police Khalid Abu Bakar confirmed he was arrested under Section 8 of the Official Secrets Act, which relates to wrongful communication of an official secret.
The Pandan lawmaker had last month exposed what he claimed is a classified document showing links between the Lembaga Tabung Angkatan Tentera and 1MDB.
He also gave a statement on the matter to the commercial crime investigations department.
Tweeting on the arrest, PKR’s Subang MP R Siavarasa said: "Will the IGP explain to the rakyat why PDRM cannot just request Rafizi to surrender himself?”
He likened it to a "kidnapping" by the police.
However, Khalid immediately reminded Sivarasa not to use words he does not understand.
— Khalid Abu Bakar (@KBAB51) April 5, 2016
PKR's Kuantan MP Fuziah Salleh said Rafizi would be taken to the Bukit Aman police headquarters.
PKR Youth strategic director Akmal Nasir told Malaysiakini that Rafizi was on the way to pick up his two-year-old son from the babysitter when the arrest took place.
"Rafizi had asked if he could come to Bukit Aman at 7.30pm after fetching his son but the police did not allow him to do so," he said.
Amanah's Kuala Terengganu MP Raja Kamarul Bahrin Shah Raja Ahmad who witnessed the arrest said he tried to speak to Rafizi, but police did not allow it.
1MDB denies causing late gratuity payments
A candlelight vigil is planned for Rafizi at Bukit Aman tonight.
Rafizi had disclosed the alleged classified document at a press conference at the Parliament lobby, however, he did not distribute the document to the media.
Malaysiakini could not report the contents of the press conference due to constraints under the OSA.
Anyone found guilty of having unauthoritised access to or disseminating classified information will be jailed for a mandatory one year or a maximum of seven years.
Responding to the disclosure, 1MDB denied it was the cause for late gratuity payments by LTAT to retired armed personnel.
It also said the document was part of the auditor-general's report on 1MDB, which was presented to the Public Accounts Committee.
The PAC is expected to conclude its probe on 1MDB this week, after which the report will be tabled in the Dewan Rakyat.
LTAT said it has made gratuity payments to most armed forces personnel in Rafizi's list, and will take the MP to court.