More than 2.5 million ballot papers and other documents used in last year's general election were set alight yesterday, part of the process to ensure the secrecy of the vote.

The sealed boxes containing the papers and documents were removed at 8.05am from the Supreme Court vault and transported to the Tuas South Incineration Plant. Prior to this, a box was opened to retrieve a copy of the register of electors for Pasir Ris-Punggol GRC's PN23 polling district, which had been accidentally sealed together with the ballot papers. The register is needed to prepare the list of electors in the area who did not vote.

Under the law, ballot papers must be sealed and kept in safe custody for six months after they are counted at the end of polling, in case of legal challenges.

They are then destroyed in front of witnesses - including election candidates from the various parties, their agents and also election department officials - to ensure that votes stay secret.

Owing to Covid-19 safe-distancing measures this time round, the number of people who could be present to witness the process had to be limited, the Elections Department said.

Pasir Ris-Punggol GRC MP Yeo Wan Ling was among those present, and had checked the 53 boxes of ballots for the constituency to make sure the tamper-proof seals were not broken. In a Facebook post, she described the experience as "amazing" and said: "Our Elections Department colleagues have done a great job keeping our ballot papers secure and safe!"

Workers' Party chief Pritam Singh, who is Leader of the Opposition, and WP member Nicole Seah represented their party.

The WP, in a Facebook post after the process, said: "Due to all these processes in place, and the presence of our volunteers as polling and counting agents, we can vouch that the secrecy of your votes is safeguarded. Till this day, there have been no reports of a ballot being traced back to a voter. Rest assured that your vote is secret, and that you would not be penalised for expressing your view on the ballot."