Vandals suspected to be loan sharks had used a lock and chain to padlock his four-room unit in Block 708, while his unsuspecting 13-year-old son was inside.

Mr Ng, 46, a marketing executive, rushed home after his wife, who had got home earlier at 6.30pm, found the grille padlocked.

Police had to break the lock.

Mr Ng was angry that the vandals had put his son at risk by trapping him inside.

He added: 'It is terrible that the loan sharks are harassing us like this, when we are not their debtors.'

Also, on Tuesday, another neighbour a floor above had his unit vandalised.

Mr Ng, who has made a police report, said harassment of units in his block by loan sharks acting for illegal money lenders went back as far as 2000.

The debtor who the loan sharks were after is believed to live two floors above.

Fearing for the safety of his only son, he has sent him to his sister's house in the past few days, as the school holidays have started.

A woman who only wanted to be known as Madam Lim, from the unit two floors above Mr Ng's, told Lianhe Zaobao that her husband did borrow money from loan sharks previously.

But that debt had been paid off five years ago, she said.

Since 2005, repeat moneylending offenders may be sent to jail while loan sharks harassing debtors may be fined between $4,000 and $40,000 and jailed up to three years.

An amendment to the Moneylenders Act in 2005, which provides for the jail terms, came into effect last year.

The maximum fine for illegal lending is now $200,000.

Previously, a first-time offender could be fined only up to $100,000.

There were 10,221 complaints last year about unlicensed moneylenders and harassment.

The figure was 1,510 in 1995.