For former PetroSaudi International executive Xavier Andre Justo, spending 18 months in Thai prison was the worst experience in his life.

He said, however, that it was worth it after seeing the outcome of the 1MDB investigation.

"Eighteen months in Thai prison was the worst experience in my life, but seeing the result and the outcome, it was worth doing it. 

"It was difficult (nonetheless)," the whistleblower told reporters when met at the sidelines of the Anti-Corruption Summit 2018 in Kuala Lumpur today.

Justo was one of the four speakers at the summit's plenary session, 'The battle against ill-gotten money: What more needs to be done'.

'If I had to do it again, I would'

In his speech, Justo told the forum that he would do the same again to reveal corruption if he had to, but would take a different approach so as to protect his family from the fallout.

He also encouraged members of the public to expose against those who are corrupt, but at the same time advised them to also be careful in doing so.

"If you must act and become a whistleblower, protect yourself, protect your loved ones. Lawyers or dedicated structures are there to help and guide you.

"Acting against criminals can be dangerous. They will do anything to keep the money, they have no limits.

"If I had to do it again, I would. Except that I would protect my family from these problems. Your loved ones should not have to suffer for your actions, whatever these actions may be," he said.

Justo said he continued to fight after his 2016 release, as he wanted those who had put him in prison and threatened his wife to cover their crimes to face justice. 

He was sentenced to three years' imprisonment after Thai police said he admitted to blackmail and attempted extortion of Petrosaudi, a Saudi Arabia-based oil and gas company.

He was released early on Dec 20, 2016 after being granted royal amnesty by Thailand's King Maha Vajiralongkorn.

Thai police also alleged that Justo had leaked documents from Petrosaudi relating to its joint venture with 1MDB that were published by Malaysian and international media groups, which formed the basis of the money-laundering investigation.

He was arrested at a Thai island resort in 2015 following allegations by Petrosaudi that he had demanded payment in exchange for not disclosing confidential information, authorities said at the time.