A man who runs a pro-government Facebook page said he was interviewed by the police last Friday over two online posts he made on the Bukit Batok by-election that allegedly violated an election advertising ban.

Mr Jason Chua, 46, a retired software engineer who runs the Fabrications About The PAP page, said on his personal Facebook page that the police served him a letter last Wednesday to go to the Police Cantonment Complex on Friday.

This followed a police report by opposition politician Augustine Lee last week. Mr Lee, from the People's Power Party, accused Fabrications About The PAP of publishing two posts on May 7, which was Polling Day of the by-election.

When contacted by The Straits Times, the police did not want to comment on Mr Chua's post, but said investigations were ongoing.

Mr Chua said he was interviewed for three hours on Friday and was allowed to go home after that.

He added that the police seized his electronic devices, including a mobile phone, a tablet computer and an external hard drive.

Election advertising, which includes posts intended to enhance the standing of a party or candidate or to promote their electoral success, is prohibited on Cooling-Off Day and Polling Day.

Mr Lee had complained that one of the two posts on Fabrications About The PAP had asked people to vote for People's Action Party candidate Murali Pillai. The other post had allegedly criticised Mr Murali's opponent, Singapore Democratic Party chief Chee Soon Juan, he said in the police report that he sent to the press last week.

The posts have been taken down.

In a separate case, blogger Roy Ngerng, former political detainee Teo Soh Lung and socio-political website The Independent Singapore are also being investigated over online posts made on Cooling-Off Day, May 6, and Polling Day of the Bukit Batok by-election.

Posting election advertising on those days is an offence under the Parliamentary Elections Act. A person found guilty of doing so may be fined up to $1,000, jailed for up to 12 months, or both.