Anti-narcotics officers arrested four men and seized more than $101,000 worth of drugs in two separate drug busts on Wednesday.

A total of about 500g of cannabis, 739g of heroin and 44g of 'Ice' were recovered by the Central Narcotics Bureau (CNB) in the two operations. Investigations against the four men - two Singaporeans and two Malaysians - are ongoing.

On Thursday, CNB said in a statement that its officers were deployed to observe suspected drug traffickers in separate operations mounted at Ang Mo Kio Avenue 5 and Paya Lebar Road.

In the Ang Mo Kio operation, a 39-year-old Malaysian arrived on a motorcycle to meet with a 33-year-old Singaporean at about 4.10pm. A search of the motorbike recovered 500g of cannabis with a street value of about $16,500 stashed in the fuel compartment. Another $1,200 in cash was recovered from the Singaporean.

At about 7.10pm that day, a 33-year-old Singaporean showed up near Paya Lebar Road on a motorcycle, parking his bike near another motorcycle belonging to a 21-year-old Malaysian. A search of the Singaporean's vehicle recovered 739g of heroin and 44g of 'Ice', while $7,750 in cash was found on the Malaysian.

The value of the drugs seized in the second bust is estimated to be more than $84,000.