HANOI: Vietnam has launched an inspection into K-pop group Blackpink's tour organiser's website, ahead of its concert in Hanoi, over criticism from fans that it shows a map of the South China Sea with disputed boundaries.

The controversy follows Vietnam's decision to ban Warner Bros' highly-anticipated film "Barbie" over a scene allegedly featuring the "nine-dash line" used in Chinese maps to illustrate Beijing's claims over vast areas of the South China Sea, including swathes of what Vietnam considers its continental shelf.

Vietnam's culture ministry said late on Wednesday it had ordered an inspection of the website "to verify the suspicion that the company organizing the Blackpink music night promoted the cow-tongue line", using the Vietnamese phrase to describe the U-shaped line.

The ministry did not immediately respond to questions about the possible outcome of the inspection. It was unclear when it would announce its findings.

Chinese organiser iME Entertainment and South Korean agency YG Entertainment, which manages Blackpink, had no immediate comment.

The organiser's website was inaccessible on Thursday but a cached version seen by Reuters and last updated on July 4, shows a vague nine-dash line that encompasses nearly the whole South China Sea.

Vietnam and China have long had overlapping territorial claims to a potentially energy-rich stretch in the waterway. The Southeast Asian country has repeatedly accused Chinese vessels of violating its sovereignty.

Blackpink, a cornerstone of South Korea's multi-billion dollar entertainment industry, is the latest to court trouble in Vietnam for depicting China's controversial nine-dash line, which was repudiated in an international arbitration ruling by a court in The Hague in 2016. China refuses to recognise the ruling.

The culture ministry's move followed complaints by Vietnamese internet users who noticed the nine-dash line on the organiser's website.

"Bought two tickets for me and my date. Then saw the cow-tongue, and quit. I am (a) patriot," Tu Anh Xinh, a Blackpink fan wrote on Facebook.

The world-famous K-pop girl group is due to perform in Vietnam for the first time ever on July 29-30, having been granted a government license that requested the organiser to comply with the government's regulations on performing activities.