Eric Ding Si Yang, 31, who is accused of trying to rig an AFC Cup football match by procuring sex workers for three Lebanese referees, was given seven days in custody because of the new charge.
Ding was being interviewed at the Corrupt Practices Investigation Bureau on Wednesday when he tried to hide a personal receipt issued by a law firm, according to court documents seen by AFP.
Local media reports said Ding stuffed the receipt in his sock after he was asked to open a safe containing his belongings. The significance of the receipt was unclear.
"The prosecution sought an order that Ding be remanded for a further period of seven days for further investigations," a spokesman from the Attorney-General's Chambers told AFP. "The court granted the application."
If convicted of theft, Ding faces a maximum of seven years in jail and a fine. He had earlier pleaded not guilty to three counts of corruption, and was granted bail at Sg$150,000 ($121,000) on April 9.
Ding is accused of supplying free prostitutes to persuade the three referees to fix an AFC Cup match in Singapore on April 3. The referees were replaced before the match and are now being held at Singapore's Changi Prison.
The case is a colourful addition to Singapore's long history of match-fixing scandals, including allegations that syndicates in the city-state organised the rigging of hundreds of games worldwide.
Ding and the three referees face maximum prison terms of five years and fines of up to Sg$100,000 for each count of corruption in relation to the match-fixing case.