Labour chief Lim Swee Say on Wednesday rejected renewed calls from Members of Parliament for a minimum wage system in Singapore.

Speaking on the second day of the Budget debate, he said that Singapore's model of Workfare Income Supplement, Workfare Training Support and a progressive wage system, works better overall than a minimum wage.

"With the WIS, WTS and the progressive wage model, we believe we have now a minimum wage model - in fact, it is more than a minimum wage model - whereby we can actually maximise the upside for the low-wage workers, and at the same time, minimise the downside," he said.

The perennial call for a minimum wage was made in the House over the past two days by MPs such as Mr Inderjit Singh (Ang Mo Kio GRC) and Nominated MP Laurence Lien, as they shared concerns that wages at the bottom are not rising fast enough, even with recent Budget measures.

Labour MP Zainal Sapari (Pasir Ris-Punggol GRC) had also expressed concern that the recently announced $3.6 billion Wage Credit Scheme - a centrepiece of the Budget - would have limited impact for these low-wage workers.

Under the scheme, the Government will co-fund 40 per cent of the pay increases of all Singaporean workers for the next three years up to a gross monthly salary of $4,000, but some low wage worker contracts may be already be fixed for the next two to three years, Mr Zainal said.

But while acknowledging Singapore was in the minority, as more than 90 per cent of countries today have a minimum wage, Mr Lim said that system had limitations, and was a "zero-sum game".

"You cannot have high upside, and at the same time a low downside," he said.