The police have arrested 12 men and five women at an illegal gambling den in Geylang which masqueraded as an association.

They picked up the suspects, aged between 28 and 73, in a five-hour joint-operation with the Immigration and Checkpoints Authority (ICA).

The police said that one of the suspects was helping to run the association as an illegal gambling den, while the rest were the den's patrons. Among these patrons, three suspects were also arrested for allegedly entering Singapore illegally and overstaying.

Four mahjong tables, four decks of poker cards and gambling chips were seized as case exhibits. Investigations are ongoing.

The operation ended early Wednesday morning.

Any person found guilty of assisting to manage a place used as a common gaming house faces a fine of between $5,000 and $50,000 and a maximum jail term of three years. As for the players, any person convicted of an offence of Gaming in a Common Gaming House faces a maximum fine of $5,000, up to six months in jail, or both.

Penalties for overstaying or illegal entry are a jail term of up to six months and a minimum of three strokes of the cane, while the penalties for illegal departure is a fine of up to $2,000, a jail term of up to six months, or both.