SINGAPORE - Former China tour guide Yang Yin, who is embroiled in a legal tussle over assets worth $40 million of a widow, was released on bail on Thursday after being questioned in connection with suspected criminal breach of trust.

Mr Yang, 40, was seen leaving the Police Cantonment Complex alone on Thursday morning. The Straits Times understands that investigations are ongoing and there are no details on when he will be charged.

Mr Yang was arrested after the police and Immigration Checkpoints Authority (ICA) hauled him in for an interview on Tuesday.

On Wednesday night, a police spokesman told The Straits Times that Mr Yang was arrested "following police reports made against him."

The arrest was the latest twist in the court battle between Mr Yang and the niece of 87-year-old widow Madam Chung Khin Chun over the control of the assets of the widow.

Mr Yang, now a Singapore permanent resident, met Madam Chung in 2008 when he was her private guide while she was on holiday in Beijing with her long-time friend Madam Chang Phie Chin.

The wealthy widow, whose husband died in 2007, has no children and was diagnosed with dementia this year. She made a will in 2010 leaving all her assets to Mr Yang, after he moved into her bungalow in 2009. In 2012, she also appointed him her guardian, giving him full control of her assets worth $40 million.

Her niece, 60-year-old travel agency owner Madam Mok, started court proceedings to revoke Mr Yang's guardianship and recover control of her aunt's assets earlier this year.

The pre-trial conference is expected to take place on Sept 24. Madam Mok has also made a police report against Mr Yang on suspicion that he may have stolen paintings and cash from Madam Chung while acting as her guardian.