Workers' Party (WP) MP Dennis Tan's allegation that PAP representatives pulled down posters during the July general election is a serious one that he must back up with evidence, said Trade and Industry Minister Chan Chun Sing yesterday.

Mr Chan (Tanjong Pagar GRC), who is also second assistant secretary-general of the People's Action Party, said: "Anyone who makes such allegations publicly should substantiate their allegations with evidence, more so when such allegations are made in this House."

On Monday, during the debate on the President's Address in Parliament, Mr Tan (Hougang) charged that the PAP had engaged in "petty and bad politics" during the election, and asked if the PAP had "gone backwards in time" in the way it conducted its campaign in Hougang.

Mr Tan said a resident had told him that she saw someone from the PAP team pulling down WP posters from the original height at which they were placed. Two complaints were later made to the Elections Department (ELD) about the posters being placed below the 2.2m minimum height requirement, and Mr Tan had to get this rectified.

Responding late on Monday, the ELD, in a press statement, said it did not receive any report from Mr Tan about his posters being pulled down, and asked him to file a report so that it could investigate. It said its approach is to get the election agent to rectify the issue within three hours, and if this is done, no further action will be taken. For the complaints it received about Mr Tan's posters, it said it adopted the same approach.

Mr Chan said Mr Tan replied to the ELD on Wednesday, saying he did not make a report to the ELD during the election as he was focusing on his election campaign, and that he had no plans to do so now.

Yesterday, Mr Chan said: "In the spirit of constructive politics that we discussed in recent days in this House, it cannot be that a member stands up to raise doubts, and does not follow through to substantiate his allegations."

He added: "ELD takes such allegations seriously and will investigate them thoroughly and impartially. This is to be fair to all parties involved, protect the integrity of the election processes and continue to uphold trust in our elections."

Mr Tan was not present in the Chamber when Mr Chan spoke yesterday. The minister asked that the ELD press statement and the correspondence between Mr Tan and the ELD be brought to the attention of MPs and entered into the parliamentary records.

On Monday, Mr Murali Pillai (Bukit Batok) had asked Mr Tan to acknowledge that the ELD had been even-handed in handling complaints it got from all political parties and candidates, which Mr Tan did.