This photo shows a screenshot of the East Sea from the map application of Apple's iPhone, Aug 25. The map does not have the name of Dokdo, Korea's easternmost islets, in the sea. Yonhap

Korea's easternmost islets of Dokdo were not named on iPhone maps in the U.S., Britain and 20 other countries, according to a professor in Seoul Thursday, amid diplomatic tensions with Tokyo over Japan's renewed claims to the East Sea outcroppings.

Dokdo has long been a recurring source of tension between the two neighbors, as Tokyo continues to make the sovereignty claims in its policy papers, public statements and school textbooks.

The name of Dokdo was not seen in 22 countries' iPhone maps, including France, Egypt and the Philippines, said Seo Kyoung-duk, a Sungshin Women's University professor well known for his efforts to promote Korean interests abroad.

Dokdo only appeared on the Apple Inc. smartphone map in Korea, while the islets were labeled Takeshima, the name Tokyo uses in its sovereignty claim to the islets, in Japan.

In 2019, Seo surveyed the online map service of Google Inc. and discovered that Dokdo was labeled Liancourt Rocks in 26 countries. The name Dokdo was only used in the Korean version of the map, while the Japanese version labeled the islets as Takeshima.

Liancourt Rocks is a name derived from a French whaling ship that first introduced Dokdo to Europe in the 19th century.

Seo said that he has protested continuously for the past three years to have Dokdo's proper name on Google Maps but the U.S. internet giant has not accepted his demand.

"It is a huge problem that maps of Google and Apple, which are searched and used by billions of people each day, don't properly label Dokdo," Seo said. The professor said he plans to push both companies again to address the problem.

Korea has been in effective control of Dokdo, with a small police detachment, since its liberation from Japan's 1910-45 colonial rule. (Yonhap)