The family of Malaysian pastor Raymond Koh has asked the country's prime minister to order a new investigation into his kidnapping.

Koh was abducted two years ago by 15 masked men in a military-style operation caught on CCTV. His vehicle was taken and has not been recovered. Attempts to discover who took him and why have so far failed.

His wife Susanna Liew told World Watch Monitor: 'It has already been two years and until now there's no result [of the inquiry]. We are at our wits' end. We don't know what else to do than to appeal to the highest authority to look into this matter and resolve it.'

She added that she admired Malaysia's new prime minister Mahathir bin Mohamad's commitment to the rule of law.

Three other victims of abduction, none of whom have been found, were also members of religious minorities in the Sunni Muslim country. Pastor Joshua Hilmy and his wife Ruth were last seen in November 2016, while Shia Muslim activist Amri Che Mat was kidnapped in an operation similar to Raymond Koh's.

Susannah Liew told an inquiry panel at the end of 2017 that she and her husband had been repeatedly harassed by Malaysian officials since 2011 and had been stopped for questioning several times by immigration and Special Branch officers when entering or leaving the country. She said she had even considered emigrating to Australia because of the stress.

Koh's daughter, Esther, told a local source she is suffering from mental torture not knowing where or how her father is.

'We are counting the days to be reconciled with him, but we are also prepared for anything,' said Liew.

The inquiry is expected to release its findings on March 6.