Workers' Party (WP) chairman Sylvia Lim has said she accepts that her suspicions that the Government had backtracked on the timing of the goods and services tax (GST) hike "may have been wrong" after she has reviewed the records.

But she refused to withdraw and apologise for her comment last week, saying she was doing her "duty as an MP to convey ground concerns, reactions and confusion".

This was despite repeated calls from People's Action Party ministers - who said Ms Lim's comments had damaged the reputations of government leaders - for her to do so.

Ms Lim said yesterday: "I did not accuse the Government of being untruthful as alleged, and neither had I intended to accuse the Government of dishonesty.

"I do not accept the over-characterisation the PAP MPs have put on my words and intentions based on their own interpretation borne out of overactive imaginations and oversensitivity."

She noted that she had raised her suspicion in the heat of the exchanges at the Budget round-up, adding: "Since the Government has now refuted it had any intention to raise GST immediately, I can accept that my suspicion then may not have been correct."

On Thursday last week, Ms Lim said she suspected the Government had intended to raise the GST immediately but backtracked after adverse public reaction. Finance Minister Heng Swee Keat announced last month that the GST will go up from 7 per cent to 9 per cent some time between 2021 and 2025.

In response, Leader of the House Grace Fu said yesterday that Ms Lim's comment suggested that the Government had "said one thing in public but (was) planning secretly to do another".

This, she added, tarnished the reputations of Prime Minister Lee Hsien Loong, Deputy Prime Minister Tharman Shanmugaratnam and Mr Heng, who have said over the years that tax revenues need to be raised in the long run.

Noting that the parliamentary privileges that MPs enjoyed came with a responsibility to check the facts and basis of their statements, she said of Ms Lim's comments: "It reflects the low standards which the member and her party have set for themselves with regard to commitment to truthful and honest debate in Parliament."

"We are deeply disappointed that someone of her experience should accuse the Government of lack of candour, even though the facts have been explained to her clearly."

The minister, who is in charge of procedure and order in Parliament, added that if Ms Lim repeats such "dishonourable conduct and abuse of parliamentary privilege", the matter will be referred to Parliament's Committee of Privileges. It can mete out penalties to MPs, including fines and jail terms.

Earlier, Ms Lim explained how she arrived at her suspicion. She cited news reports and economists who had predicted that the GST rate would be raised this year or the next. The public was also worried about an imminent hike, she said.

She also said that the Government "contributed to this suspicion by its non-denial of reports and economists' predictions of an immediate GST rise".

Ms Lim also cited PM Lee's statement in last year's debate over Oxley Road, during which he told MPs: "If you think something is wrong, even if you are not fully sure, then come to this House, confront the Government, ask for explanations and answers."

She queried: "Is there a difference in standards here - when the PM's name needs to be cleared and when we are talking about raising taxes on the people?"

Ms Fu said that there is nothing wrong in MPs representing their constituents by surfacing their views. But they must check the facts before they "bring the opinions, the speculations, the views, the unhappiness to this Chamber", she said, noting that Ms Lim had admitted to not taking this step.

The exchange, which lasted 22 minutes, also saw Mr Heng weighing in. He said that the Government could not have made any earlier announcements on the GST hike, explaining: "We take great care in preparing the Budget and the details are kept secret until the day of the Budget, because it has an impact on the market, and not just in Singapore, but internationally."

To this, Ms Lim said that she could not say for sure what the position was as "only the Cabinet knows the truth of the GST hike" .

Stepping into the exchange, WP chief Low Thia Khiang said that the Government could have said earlier that it had no intention to raise the GST at this Budget, "and that would have cleared the air and the confusion on the ground".

"Now, it is clear that the Government has no intention to raise GST at that point in time and her suspicion wasn't really correct at that point in time."

Mr Heng said he could accept that Ms Lim could have said things that she did not intend in the heat of the exchange. But now, would she accept that there was no backtracking by the Government?

To this, Ms Lim repeated her position that while she accepted she might have been wrong in her suspicion, she saw no reason to apologise.