SINGAPORE - A company director lied to police after pirates hijacked a tanker his firm had chartered - because he did not want the authorities to know that it was carrying 2,000 tonnes of crude oil which had been purchased illegally.

Louis Lau Xuanhong, 34, was sentenced to two weeks' jail on Monday (June 3) for giving false information to the police, along with three weeks' jail and a $4,000 fine for a separate drink-driving charge.

Lau worked for Yu Tat wholesale trading company, which chartered the Singapore-registered MT Joaquim. It collected the oil from a Maltese vessel in the Strait of Malacca before being hijacked by pirates on Aug 8, 2015.

The court heard that Lau called the bunker clerk of Prosperbiz Petroleum, Lim Puay Kwang, 41, asking him to lie to the Malaysian authorities and say that pirates had hijacked MT Joaquim while it was sailing towards Langkawi to deliver cargo to a firm called Siam Gulf Petroleum. In reality, MT Joaquim was on its way back to Singapore.

Worried that Singapore's Police Coast Guard might also question them about the illegal purchase of the crude oil, the pair met Prosperbiz's director - 55-year-old Chew Hoe Soon - at a Beauty World Plaza eatery on Aug 10, 2015, where the trio agreed to lie the Singapore police.

It was not revealed in court documents what Lau had originally intended to do with the oil, or how Singapore-registered Prosperbiz was linked to him.

Lau gave the false information to Station Inspector Sivaprakash Damohdaran at Central Police Division the next day, while Lim and Chew lied to the Police Coast Guard later that month.

All three Singaporeans retracted their false statements about three months later, the court heard, though it was not revealed why.

Chew was earlier sentenced to two weeks' jail, while Lim was fined $3,000.

The MT Joaquim was found off Pulau Rupat in Indonesia's territorial waters.

Separately, Lau's breath-alcohol level was found to be more than twice the legal limit when he was stopped by police in Kallang Road at around 4am on Feb 13 this year. He had earlier drunk six glasses of beer. He committed a similar offence in 2011.

Lau was also disqualified from driving all classes of vehicles for three years on Monday.

He is now out on bail of $10,000 and must surrender himself at the State Courts on July 22 to begin serving his sentence.

For giving false information to a policeman, he could have been jailed for up to six months and fined up to $5,000.

First-time offenders convicted of drink driving can be jailed for up to six months or fined between $1,000 and $5,000. Repeat offenders can be jailed for up to a year and fined between $3,000 and $10,000.