Despite a plea for leniency by her lawyer, Ong Hock Sung was sentenced on Jan 29 for subletting a house to tenants without proper documents for S$150 (US$86) a month each after being warned by police three months earlier to check their particulars.

When police told Ong to look over the passports and work permits of her tenants, she replied that she could not read and would get someone to help her with the checks, the Straits Times newspaper reported Jan 30.

"I can't go to jail," Ong said outside the court, surrounded by three of her seven grown up children. "My health is poor. I get giddy spells."

No one from the court office was immediately available to comment on the case.

Singapore issues visas to thousands of foreign workers -- mostly from Bangladesh, Indonesia, Malaysia and the Philippines -- for tasks such as construction, landscaping and child-minding.

But the rich island state is also a magnet for illegal immigrants and overstayers. Immigration officers routinely discover people being smuggled into Singapore in car boots and modified trucks with secret compartments.

In December, four Bangladeshis and one Malaysian were found in the cramped toilet of a tourist coach as they tried to sneak into Malaysia after staying illegally in Singapore.