The number of one -star ratings for the Facebook app on Apple’s App Store surged by 50 percent in a day to more than 60,000 on Friday, according to data analysis service AppBot.

The number of reviews jumped almost fivefold on Thursday to 7,700, with 92 percent of them labeled as "negative."

This has resulted in ratings of the app falling from 3.1 over 5 stars on Thursday to 2.9 on Friday.

The reviewers said the Truong Sa (Spratly) and Hoang Sa (Paracel) Islands are part of Vietnamese territory and not China’s.

They put up Vietnamese flags and demanded that Facebook correct its map.

Vietnamese users say the Spratly and Paracel Islands belong to Vietnam in
their reviews of the Facebook app on Apple's App Store. Screenshot
by VnExpress/Dat Nguyen.

Many users also commented on Facebook CEO Mark Zuckerberg’s page demanding that this be fixed and threatened a boycott if he failed to do so.

"Hoang Sa Truong Sa Islands belong to Viet Nam!!! Fix it or we will abandon this application," Ha Uyen warned.

Vietnamese users say the Spratly and Paracel Islands belong to Vietnam on
CEO Mark Zuckerberg's Facebook page. Screenshot by VnExpress/Khuong Nha.

Facebook users in Vietnam said on Wednesday they found the Spratly and Paracel Islands shown as Chinese territory in an ad creating function on the app.

Facebook has said the islands' disappearance from the Vietnam map was caused by an error when the map was updated, Le Quang Tu Do, deputy director general of the Authority of Broadcasting, Television and Electronic Information, said.

A Facebook spokesperson said on Thursday there was a technical glitch involving the location maps used in its ads targeting tools in Vietnam.

"This issue has now been fixed. We are very sorry for any confusion this has caused."

Facebook does not take a position on border disputes or other geographical sensitivities, the spokesperson added.

The map section used for Facebook's ad creation function is sourced from OpenStreetMap, an open-data, editable map project based in the U.K.

In 2018 too Facebook had wrongly shown the archipelagoes as part of China in its ad creation section. It fixed the error later, claiming then too it was a technical issue.

Vietnam has consistently said it has full legal basis and historical evidence for its sovereignty over the Paracel and Spratly Islands in the East Sea, internationally known as the South China Sea.

China seized the Paracel Islands from South Vietnam by force in 1974, and has been illegally occupying a number of reefs in the Spratly Islands since 1988.