Their presence near Kampong Glam have been described by businessmen and residents there as 'an eye sore'.
The shopowners want to preserve the area's cultural charms.
Said Dr Ameen Talib, chairman of the Kampong Glam Business Association (KGBA): 'The North Bridge Road area is the entrance to Kampong Glam and Sultan Mosque, a symbolic centre.'
To have such activities here is unacceptable, he added.
Dr Ameen was referring to the karaoke pubs and bars at North Bridge Road and its sidelanes, Aliwal Street and even at Golden Landmark.
While the nightspots are located outside the core area stipulated by the Urban Redevelopment Authority for conservation, the entertainment sites have been lately attracting more foreign women.
Even on week nights, scores of foreign girls congregate outside karaoke lounges.
On weekends, it gets busier, said coffeeshop helpers nearby.
It is understood that the foreign women, some of whom are from China, make a living from tips received at the karaoke pubs.
The girls earn more if they are able to secure 'private arrangements' with male clients, said Mr Nick Tan, 27, who is familiar with the night scene there.
There are at least seven bars and karaoke pubs within walking distance of Kampong Glam.
At night, the women make their rounds from one karaoke bar to another.
Said Mr Tan: 'If business is bad at the karaoke bars, there's nothing stopping them from improvising.
'I have seen some girls chatting up men waiting at the bus stops and even at the coffeeshops along North Bridge Road. Once a price is agreed, they will adjourn to a hotel nearby.'
Dr Ameen said eight people from the Kampong Glam community have complained to him about the intrusion in the last two weeks.
Added Dr Ameen: 'Our dream is to have an alcohol-free zone in Kampong Glam. This area has so much heritage and we would like to promote it as a family-friendly area.
'In Singapore there are many places where people can get drunk, but there are not enough places where people can go to for decent fun.'
The manager of House of Briyani along North Bridge Road said she had noticed the girls over the last three months.
Said the woman who wants to be known only as Madam Su: 'Some of them eat at my restaurant and they don't seem like troublemakers.
SLEAZE MOVES SOUTH
'While none of my customers have been harassed by the women, it is sad that Geylang's sleaze has moved south towards Kampong Glam. It seems that there are now more girls and local men in the vicinity at night.'
By 9pm when Madam Su closes up, the parking lots beside her restaurant would be all taken up.
Men would head for the karaoke bars and later drive off with female companions.
Currently, it appears the foreign women have not dared to venture into the heart of Kampong Glam like Baghdad Street or Bussorah Street.
A convenience store worker said the women would normally buy snacks or drinks from her before going to 'work'.
And to get to their work place, some make detours by walking along dark backlanes leading to Victoria Street.
Police spokesman Mohd Razif said public soliciting in Kampong Glam is not common.
Last year, 4,300 foreign prostitutes were arrested island-wide as compared to 3,220 in 2005.
The police will continue with strict enforcement action against errant operators and persons associated with vice.