SINGAPORE - Vice remains a scourge in some heartland estates despite recent police raids, even as MPs call for residents to keep an eye out as well for vice activities in their neighbourhoods.

Despite a raid last week in which one man and 96 women were arrested in more than 40 locations, online listings of women promising sexual services remain.

On one website, about 280 scantily clad women in provocative poses promised services ranging from massages to sex for prices between $80 and $280.

Posing as a customer, this reporter took just half an hour to contact and elicit responses from a number of women who listed their phone numbers on the site. Ten out of 20 contacted replied, with six saying they could be found in condominiums in areas such as East Coast Road, Tanjong Katong Road and Upper Serangoon Road.

Three were in HDB flats in Bedok South and Yishun, with two naming the same block in Bedok South. One claimed to work in a massage parlour in Serangoon Garden.

Of the remaining 10, six did not answer while three did not continue the conversation. One said she was taking a break and would resume her services only early next month.

To stem this paid sex from cropping up in their estates, communities need an "all-out approach", said Mr Patrick Tay, a former policeman who sits on the Government Parliamentary Committee for Home Affairs.

One way is for neighbours to inform the authorities when they suspect that vice activities are going on in their area, he said.

Mr Tay said: "We need to be concerned about the influence that sex workers may have on the neighbourhoods and the young children living in them."

In the anti-vice raid last week, the most extensive conducted in heartland areas so far, the suspects were arrested in HDB flats, hotels and condominium units in locations including Yishun, Jurong and Chinatown.

Local press reports said those nabbed were all foreigners.

On Thursday (Jan 18), The Straits Times visited two Housing Board units in Ang Mo Kio and Jurong West where women were still selling sexual services as recently as in October last year.

Neighbours said that the two flats are now vacant.

At the unit at Jurong West Street 61, two dusty letters from the electricity and gas department lay outside the door. At Ang Mo Kio Avenue 8, knocks on the door behind the padlocked gate went unanswered.

More should be done to study how best to address vice in the heartland, said Mr Louis Ng, who is on the same committee as Mr Tay.

Mr Ng noted sex workers may simply move to other units, since they use the Internet or social media apps to trawl for customers.

His fear is the sex trade will be driven underground, and "it becomes a cat-and-mouse game between the authorities and the sex workers".