SINGAPORE - A pan-island police operation clamping down on illegal horse-betting activities has led to the arrest of 33 men, the oldest of whom is 81.

Some $9,000 in cash, as well as mobile phones and bookmakers' notebooks, were seized from multiple locations, including Toa Payoh, Eunos Crescent and Boon Lay Place, during the raid on June 3.

The police said the 33 men are being investigated for potentially breaching safe distancing measures, in addition to gambling offences.

"The police will continue to clamp down on criminal activities, including illegal gambling. Those found engaging in such activities will be dealt (with) sternly in accordance with the law," they said in a release on Friday (June 5).

If found guilty of betting with a bookmaker, the 33 men can be jailed for up to six months, fined up to $5,000, or both. Those who are involved in bookmaking can be fined between $20,000 and $200,000 and jailed for up to five years.