MANILA, Philippines — Beyond looking into how Chinese fishing vessel Yuemaobinyu 42212 hit the Filipino fishing boat Gem-Ver 1 near Recto Bank in the West Philippine Sea, the government should stress that it was in the Philippines' exclusive economic zone, Vice President Leni Robredo said Sunday.

Speaking on her weekly radio show, Robredo said that she was surprised that President Rodrigo Duterte had agreed to a joint probe with China into the incident. She pointed that Foreign Affairs Secretary Teodoro Locsin Jr. had already said the two countries would hold parallel investigations.

"I thought that was where we were going, but suddenly we are doing a joint investigation," she said in Filipino.

Presidential spokesperson Salvador Panelo announced Saturday that the president "welcomes and accepts the offer of the Chinese government to conduct a joint investigation to determine what really transpired in Recto Bank and find a satisfactory closure to this episode."

Robredo said she is wary of a joint probe with China, "since the main issue is that Filipinos were bullied," adding she would prefer a multilateral approach, a point also raised by other members of the Liberal Party.

She raised the initial statement from the Chinese embassy, saying the Yuemaobinyu 42212 left the Filipino crew of the Gem-Ver 1 because they were afraid of being "besieged" by Filipino boats nearby, an assertion that it did not repeat in a follow-up statement.

"The Filipino fishermen really disputed that because they said they were the only boats there when it happened. That's why a joint investigation is difficult, we don't know if the truth will really come out," she also said. She said the Philippines and China can investigate separately while a neutral third party can hold a separate probe.

Although most of the opposition to the joint probe has come from members of the Senate minority and of the Liberal Party, Sen. Panfilo Lacson on Sunday also raised concerns about the planned joint probe.

"The government must seriously consider the issue of sovereignty in the conduct of a joint investigation with China. The 2016 Hague ruling expressly states that Recto Bank is part of the Philippines’ 200-nautical mile [exclusive economic zone]," Lacson, a member of the Senate majority bloc, said in a tweet.

"It is ours. Are we waiving ownership of Recto Bank?" he also said.

President Duterte has said the Recto Bank allision is not an issue of sovereignty since the incident did not happen in Philippine territorial waters.

According to the UN Convention on the Law of the Sea, countries have special rights over resources found in its exclusive economic zone.

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Recto Bank is in Philippine EEZ

Robredo also said that Recto Bank is in the Philippines' 200-nautical mile exclusive economic zone, "it's called the exclusive economic zone because it is us who have the exclusive rights to utilize and enjoy the resources there."

Robredo, who visited the captain and crew of the Gem-Ver 1 in Occidental Mindoro last week, said that the fishermen were not able to ask why the Yuemaobinyu 42212, which China has said was fishing in the area, was there at all.

"There are some who were asking what the Vietnamese fishing boat (that rescued the Filipinos) was doing there, but the primary question is what was the Chinese fishing boat that collided with the Filipinos doing there?"

She said that that should be included in the investigation. "We are calling on the [Bureau of Fisheries and Aquatic Resources] because it is the agency that is directly responsible for that," she said.

Agriculture Secretary Emmanuel Piñol said last week that the Vietnamese fishermen who had rescued the 22 Filipino fishermen of F/B Gem-Ver 1 hours after the boat sank from damage from the allision should not have been in the Recto Bank.

"Thank you to the Vietnamese for helping, but you are not supposed to be there but thank God you were there. That was an illegal act that was actually providential," he said on June 19.

He said Cabinet officials had agreed not to punish the Vietnamese in recognition of their helping the stranded Filipinos.

The Palace, on June 17, said that the Chinese vessel was not allowed to fish in the Philippine EEZ, but also said "we do not know yet if they were fishing there."