An oil tanker chief engineer was sentenced to 18 months' jail on Thursday after he was found guilty of siphoning 200 metric tonnes of marine fuel oil worth US$125,400 (S$153,359).

But Greek national Pittis Stavros, 58, is appealing.

Bail of $120,000 has been offered pending his appeal, and he is scheduled to leave for home early Friday morning.

Stavros - a chief engineer of the MV Sakura Princess which was chartered by V8 Pool Inc - was found guilty last week of criminal breach of trust.

On Jan 10 last year, bunker company Constank had been nominated to supply 1,800 metric tonnes of marine fuel oil to Sakura Princess, the prosecution said. A bunker clerk on board the Coastal Saturn was deployed to supply the vessel with 500 metric tonnes of oil, as the vessel claimed it needed fuel urgently.

Stavros struck a deal with an independent surveyor and the bunker clerk to short-change his vessel of 200 tonnes of fuel.

He told the two men separately he wanted "business", meaning that he wanted to enter into a buy-back arrangement with them, where fuel is sold back to the supplier.

He sold 200 tonnes of oil for US$40,000, which was meant to cover both his payments as well as the surveyor's, as the latter had also asked for a fee.

That day, officers from the Maritime and Port Authority and anti-graft agency arrested Stavros and others.

Arguing for a stiff sentence, Deputy Public Prosecutor Sanjiv Vaswani said there was a strong need to deter illegal activities in the bunkering industry to safeguard Singapore's reputation as a premier bunkering destination.

More than 42 million tonnes of marine fuel was sold here last year, making Singapore the world's top bunkering port.