The Ministry of Foreign Affairs Thursday reiterated its call for China to cooperate in searching for nine fishermen who are still missing after they were allegedly released by Chinese officials on Monday.
The ministry had made the same demand on Wednesday in a meeting with Chinese Embassy.
The fishermen were illegally detained on September 11 when they were fishing in Vietnamese waters off the coast of the Hoang Sa (Paracel) Archipelago.
China accused them of using explosives when shipping and asked for 70,000 yuan (US$10,461) in fines.
However, following Vietnam's demands that it free the fishermen and their boat unconditionally, China early this week said it had released the fishermen Monday.
It claimed that the boat was provided with all necessary equipment and enough fuel, and they'd left at 1 p.m. that day.
At a press meeting Thursday, foreign ministry spokeswoman Nguyen Phong Nga cited the Chinese embassy as saying the boat had returned later asking for more fuel and that this was given.
According to the embassy, a tropical depression then was hitting the East Sea, so Chinese officials had advised the Vietnamese fishermen about staying for another couple of days, but they insisted on leaving and signed an agreement that they will be responsible for their decision.
The fishermen officially left Monday night, the embassy said.
Experienced fishermen in the central province of Quang Ngai's Ly Son island district, the fishermen's native place, said they should have reached home by Wednesday at the latest.
Nguyen The Tung, an official at the Vietnamese Embassy in China, told Thanh Nien on the phone that when China released fishermen it had detained in the past, they were either handed over to Vietnam's representatives, or the fishermen went home by themselves.
In this case, China didn't hand them over, but just announced that it had released the fishermen, Tung said.