SINGAPORE - A former cop asked his old buddy who was still in the Singapore Police Force to arrest a man he alleged was involved in drug activities, bookmaking and illegal betting.

Tan Bee Song offered 47-year-old investigation officer Shukor Bin Warji $2,000 to nab one Mr Hoon Tian Jie, which he turned down.

However, Shukor was sentenced to a week's jail on Tuesday (March 27) for failing to arrest his former colleague for trying to bribe a police officer.

Shukor was sentenced on one count of prevention of corruption and had another offence under the Official Secrets Act taken into consideration.

Shukor was working at the Central Police Division, specialising in investigating unlicensed moneylending, when 40-year-old Tan asked for his help in July 2016 - saying he would split $4,000 he had been offered to get Mr Hoon arrested.

The court heard one Yee Kok Siong, 32, had offered Tan the sum to get "revenge" on Mr Hoon for "playing (him) out" and even more money was on the table if Mr Hoon was imprisoned.

Tan gave Mr Hoon's particulars to Shukor on a piece of paper, which Shukor kept. It was not mentioned in court whether Mr Hoon was indeed involved in illegal activities.

Shukor turned down the bribe, saying Mr Hoon's alleged offences were not in his specialist branch. However he did not report the offer of a bribe to his superiors, or arrest Tan for trying to bribe a police officer.

District Judge John Ng said that while it was "not easy" for Shukor to arrest a friend and former police officer, Shukor was "duty-bound to act".

Shukor is currently interdicted from the SPF and is out on bail for $15,000 and will commence his sentence on April 9. Tan and Yee's cases are still pending.

For his failure to arrest Tan, Shukor could have faced up to six months in jail or fined $5,000 or both.