He had been at the National University of Singapore (NUS) for 12 years, and was a senior research fellow and an environmental expert.

But that did not stop Durairaju Kumaran Raju, 50, from hatching a plan to recover money spent on himself, and on one occasion guests he had entertained, at various tourist attractions. Between 2012 and 2014, he submitted five invoices to claim reimbursement for 309 transport hours when fewer hours had, in fact, been used. The inflated transport claims were to mitigate the other expenses.

But an NUS internal audit in March 2014 uncovered his ruse.

Durairaju, who was with the Tropical Marine Science Institute, was sentenced to four weeks' jail after pleading guilty to five charges of deceiving NUS by seeking claims.

District Judge Lim Tse Haw had sentenced him to two weeks' jail on each charge, with two of the terms to run consecutively.

In explaining the jail term in decision grounds issued on Wednesday, Judge Lim said public funds from various government agencies, including statutory boards, were used to reimburse Durairaju.

Ravichandran Samikkanu, 51, the transport owner who provided the services, was jailed two weeks after pleading guilty to falsely inflating the hours on the invoices for Durairaju to forward to NUS. He was given one week's jail for each of the five charges, with the first two terms to run consecutively, given his lower culpability, said the judge.

Ten other charges were taken into consideration by the court which heard that NUS had paid out $8,490 in inflated transport claims.

Both men had engaged lawyer Low Cheong Yeow, who urged that they be fined. He said they had made full restitution and regretted the means used to cover the various expenses properly incurred when hosting foreign research fellows in Singapore.

However, Deputy Public Prosecutor Norman Yew argued that the multiple offences were premeditated and carried out systematically over a long period. Durairaju had also breached NUS' trust in masterminding the scam.

Judge Lim said the duo may be entitled to be reimbursed for meal expenses, but other items cited like tickets for tourist attractions for the foreign research fellows were expenses for which there was no avenue for reimbursement.

The judge added that even for meal expenses, Durairaju had circumvented the controls put in place by NUS through his deception as he then did not have to show the reasonableness and necessity of each expense.

"Without the necessary controls, there was nothing to prevent Durairaju from entertaining his foreign research fellows at expensive restaurants which may exceed what would have been reasonable meal expenses. In any event, he was not allowed to make such claims from the Grantors' fund," said Judge Lim.

Both men are appealing against the sentence and are out on bail.

An NUS spokesman said yesterday Durairaju's employment with the university ended in 2014.