SINGAPORE, April 20 (Reuters) - Singapore prosecutors on Tuesday filed five additional charges against businessman Ng Yu Zhi in relation to a scheme that allegedly raised at least S$1 billion ($746 million) from investors to fund bogus nickel trades.

The alleged fraud, one of the city-state's biggest, follows a string of scandals involving Singapore trading firms that have shaken investor and banker confidence in the sector over the last year when some commodities, including nickel, have rallied strongly.

The new charges of cheating against Ng were read out in Singapore's State Court.

The charges allege that Ng, former managing director of commodity trader Envy Global Trading Pte Ltd and Envy Asset Management Pte Ltd, deceived five individuals on multiple occasions into investing about S$8.8 million in connection with non-existent forward nickel contracts.

Last month, Ng was charged with two counts of cheating and two of fraudulent trading. It is unclear how many investors in total were entangled in the scheme.

Ng, who was in court on Tuesday, and his lawyer declined to comment. Police have seized about S$100 million worth of his assets.

Fraudulent trading can carry a prison term of up to seven years in Singapore, while cheating is punishable by a jail sentence of up to 10 years.

The next court hearing in Ng's case is due on May 17.

($1 = 1.3263 Singapore dollars) (Reporting by Chen Lin in Singapore Writing by Aradhana Aravindan and Mai Nguyen Editing by Ed Davies)