Activist Sheila Sandhu and her husband have been arrested by police.
According to Bersih secretariat manager Mandeep Singh, the couple is being detained at the Dangi Wangi district police headquarters.
Mandeep said the arrest may be linked to a Facebook post Sheila made.
He disclosed in a Facebook post that the investigation was under Section 233 of the Communications and Multimedia Act 1998.
Section 233 of the law concerns improper use of network facilities or service with the intent to annoy, abuse, threaten or harass another person.
It is unclear what is the offending Facebook entry being investigated by police but prior to Sheila's arrest, she criticised the arrest of Bersih chairperson Maria Chin Abdullah.
Sheila had taken aim at KL police chief Amar Singh and questioned his credentials as a Sikh over Maria's detention.
The post subsequently went viral with some Sikh Facebook users criticising the mixing of religion in the matter.
Maria was arrested on Nov 18, a day before the Bersih 5 rally.
She was detained under the Security Offences (Special Measures) Act 2012 which allows for detention without trial for up to 28 days.
The investigation was over grants received by Bersih from Open Society Foundations (OSF). -Mkini