Casino regulators have imposed more than $500,000 worth of penalties on the two casino operators here for various breaches between May and December 2012.
The regulatory breaches included failing to stop Singapore citizens and permanent residents from getting in without paying entry levies; letting in those who had been banned, and letting in minors under 21.
Marina Bay Sands (MBS) will bear most of the financial penalties, after it allowed in 12 people without valid entry levies and 16 with exclusion orders, and five people to remain after their valid entry levies had expired.
It will have to pay $337,500.
Resorts World Sentosa (RWS) will have to pay $190,000 for allowing 12 people in without valid entry levies, one to stay on after his levy expired, five with exclusion orders, and five foreign minors.
The Casino Regulatory Authority said in a statement it takes a "serious view" of these lapses, but acknowledged the operators' measures to comply with rules, including conducting more through checks at entrances, detecting levies about to expire, and improving physical infrastructure like gated entry gantries.