MANILA - The joint investigation of the Philippines and China on the Recto Bank incident, wherein a Chinese vessel allegedly sunk a boat of 22 Filipino fishermen and left the Filipinos adrift at the West Philippine Sea, was described as a "joke" by a former top official of the Association of Southeast Asian Nations (ASEAN).

Dr. Wilfredo Villacorta, deputy secretary-general of ASEAN from 2003-2006 and former ambassador and representative to the international body, said the joint probe of the two countries is strange and unheard of, and is also a "laughing stock" in international relations.

"It (joint Philippine-China probe) is a joke. The accused being part of the investigation? I've never heard [of] any such situation, [even] in the movies," Villacorta told ANC.

Villacorta, a professor emeritus of De La Salle University Manila, said the Philippines should have a separate investigation on the Recto Bank incident.

"We are the victims. We don't have to involve China," Villacorta said.

Manila declined on China's proposal of a joint investigation on the incident last June 21.

However, President Rodrigo Duterte announced Saturday he agreed to a "joint and impartial investigation" between the two countries.

The President himself expressed his "doubts" if the joint investigation will bring a resolution to the Recto Bank issue.

Villacorta said the joint investigation, if it would continue, should not turn into a under-the-table negotiation since China is a superpower.

He added China will do everything in its power to avoid being incriminated.

"A country like China would not want to be portrayed as the villain, so it will do its best to exonerate the party involved in this case," Villacorta said.

The former diplomat said he hopes Duterte will "manage the issue well" especially since the the President already has given the go-signal for the joint investigation.