The organizers of a Cambodian beauty pageant have been forced to acknowledge their use of a historical photograph from Thailand, saying the mistake was unintentional and resulted from “insufficient verification” of the original sources.

The Miss Universe Cambodia pageant came under fire on social media after images of women dressed in traditional attire were displayed on stage during the pageant’s preliminary round last week, along with a description saying they were wearing traditional Khmer clothing.

One of the photographs, which showed seven Thai women in traditional dress, was taken in Kamphaeng Phet province in 1906, during the reign of King Chulalongkorn. According to the Bangkok Post, the photograph is part of a large collection of glass-plate negatives that is preserved at the Phra Vajirayana Royal Library in Bangkok.

The revelation prompted a social media flame-war between Thai and Cambodian nationalists, each of whom accused the other of stealing or appropriating the other’s culture.

Thailand’s Ministry of Culture subsequently sent a letter to the pageant organizers on Monday, demanding an apology and correction for its use of the Thai photograph, which it said “was done intentionally to cause misunderstanding about the picture’s origin,” the Bangkok Post reported. Culture Minister Sabeeda Thaised told reporters that the original photograph contained a watermark, which the Miss Universe Cambodia organizers appeared to have cropped out.

The Miss Universe Cambodia statement, signed by the pageant’s national director Prasat Davin, said that the photograph was intended to highlight the traditional sbai garment, and that its incorrect attribution resulted from “insufficient verification of the original sources of those images.”

“We would like to emphasize that there was no intention to cause misunderstanding, controversy or offend the feelings of any member of the public, whether nationally or internationally,” it said.

Disputes over cultural “ownership” have been a perennial occurrence in relations between Thailand and Cambodia. A long history of cultural cross-pollination between the two nations and their respective premodern civilizations has produced a close overlap in cultural practices, including dance, cuisine, architecture, and sports like kick-boxing, as well as the two countries’ Sanskrit-derived writing systems. In spite of these cultural affinities, or perhaps because of them, the question of ownership is a highly emotive issue – one that can sometimes have real-world impacts.

For instance, in 2003, Khmer-language press reports claimed that a Thai actress said that Cambodia had “stolen” Angkor Wat, and that she would not visit the country until it was “returned” to Thailand. In response, mobs of protesters sacked the Thai Embassy and numerous Thai businesses, causing millions of dollars in damage.

Such cultural disputes have also complicated the resolution of the long-standing frontier dispute between Cambodia and Thailand. The two nations’ land border is dotted with ancient Khmer temples that are shot through with nationalist significance, particularly for the Cambodian side. One of these is Preah Vihear temple, a glorious 11th-century Angkorian temple perched on a cliff on the two nations’ border.

In 1962, the International Court of Justice ruled that Preah Vihear belonged to Cambodia, but Thai nationalists have never accepted the verdict. When UNESCO listed the temple as a World Heritage Site in 2008, royalist protesters heaped pressure on the Thai government and helped precipitate a bilateral crisis that flared into armed conflict on several occasions between 2008 and 2011.

The border dispute again resulted in armed conflict on two occasions last year, embittering relations between Phnom Penh and Bangkok – and between dueling nationalist cohorts online. In the context of the current stand-off, Thai-Cambodian disputes over cultural ownership have become more acute and potentially combustive than ever.