A married businessman has been jailed for a month after he unlawfully wed in Las Vegas another woman who is more than 30 years younger.

Ronnie Oh Yin Yan, 58, director of three Singapore-based businesses including tent rental company Sin Hiap Mui, pleaded guilty yesterday to contracting a marriage with the 26-year-old woman in the US. This union is now void.

Oh legally married his Singaporean wife, now 56, on Oct 20, 1987. The Straits Times understands that they are still together.

He befriended the younger woman online in April 2016 and the pair started a romantic relationship four months later.

Deputy Public Prosecutor Ben Mathias Tan said Oh paid the woman a monthly sum to work in his firm and for companionship. He later told her he would raise her allowance if she married him.

Court documents did not reveal the amount he was giving her. The woman accepted his proposal and he suggested tying the knot in Las Vegas. They registered their marriage there on March 28 last year.

Court documents did not state if the woman knew that Oh was already married. They also did not reveal how the offence came to light but the court heard that Oh admitted to it during an investigation.

Oh, who was unrepresented, told the court yesterday that he quarrels with his legally married wife every day. He also said that he is now on medication to treat ailments, including high blood pressure.

Oh could have been jailed for up to seven years and fined for committing the offence.