Candidates who posted election advertisements on social media yesterday were reminded by the Elections Department (ELD) of the ban on electioneering on Cooling-off Day.

There were several election advertising posts on Twitter and Facebook by a few candidates and parties in the early hours of yesterday.

The ELD named the People's Action Party (PAP), People's Power Party (PPP) and Reform Party.

"Upon noticing these postings, the Assistant Returning Officer reminded these candidates and parties of the rules which prohibit election advertising on Cooling-off Day," the ELD said in a statement.

The posts have since been taken down.

Minister for the Environment and Water Resources Vivian Balakrishnan, a PAP candidate in Holland-Bukit Timah GRC, was among those whose Facebook and Twitter accounts were updated. In a post just before 2am, he described his day of campaigning in the GRC's Cashew ward. He later said his Cooling-off Day posts were an automatic repeat of a Facebook post he had originally uploaded on Sept 4. As his Facebook and Twitter accounts were linked, a Twitter post was automatically generated as the Facebook post was uploaded, he added. "We have contacted Facebook to conduct an investigation into the source of this bug. We have also requested that the page be locked down to prevent any further postings."

The police confirmed a report was made on Dr Balakrishnan's election activity, and said they were looking into the matter.

As for the PPP, a video of its secretary-general Goh Meng Seng's rally speech on Wednesday was posted on its Facebook page after midnight. Mr Goh said the page's administrator "took longer than expected to upload the speech, hence the mistake".

RP's chairman Andy Zhu said a member shared a post calling for volunteers and polling agents on the Facebook page of its youth wing. The member was abroad and unaware of the time difference, he added.

On Cooling-off Day, candidates cannot campaign and election advertising must not be published, to let voters reflect rationally on issues raised during the election period before voting.