Communications and Multimedia Minister Datuk Seri Ahmad Shabery Cheek challenged the opposition to deny having met former PetroSaudi director Xavier Andre Justo to buy classified data.
"If they cannot deny the fact, then it will go to show the people that such allegations are true," he said.
Thai police claimed that Justo had met a prominent leader from the opposition before allegedly selling classified information about the company.
Justo had admitted to meeting the individual at a hotel in Singapore.
Ahmad Shabery said if former journalist Lester Melanyi's claims in a video that the opposition had conspired with Sarawak Report to publish forged documents on 1Malaysia Development Berhad (1MDB) was true, it shows that there was a conspiracy to bring down Prime Minister Datuk Seri Najib Tun Razak.
"I have seen the video and the confession was shocking and can be an important evidence to prove that the conspiracy was serious," he said.
Defence Minister Datuk Seri Hishammuddin Tun Hussein said the opposition must clarify claims in the video.
"They must prove the validity of such claims in the video because if it is true, it is a serious matter...but I do not want to accuse anyone," he said.
A special task force is currently investigating claims reported in US business paper the Wall Street Journal that US$700 million (S$943 million) from state-owned 1MDB was channelled to Prime Minister Datuk Seri Najib Tun Razak's personal bank accounts.