Authorities were also seeking to arrest five other policemen in connection with the crime, the official said.

'I cannot imagine how the public must feel about this case,' deputy commander Police Major General Watjanon Tirawat told reporters.

'We have set up a committee to investigate this case. We will continue to protect innocent people from wrongdoers,' he said.

On Sunday, around five or six policemen entered the 42-year-old woman's luxury home in Bangkok, falsely accusing her of drugs offences and kidnapping her and her two sons, aged 10 and 15, police said.

The woman owns a garment factory.

The three were kept in an apartment in the Thai capital but freed unharmed on Tuesday after the woman withdrew 8.6 million baht from her bank accounts.

While she was taking out money from her bank and depositing it into one of the kidnappers' accounts, her sons were held in the apartment as hostages, police said.

The case became public after her husband reported the crime to police. -- AFP