Indonesia's president expressed concern on Sunday after Malaysia's Southeast Asian Games organisers mistakenly published the Indonesian flag upside-down in a commemorative magazine, prompting anger amongst fans.
Malaysia's foreign ministry and the Games organisers apologised profusely for the gaffe but it was not enough to quell a wave of complaints online, with #ShameOnYouMalaysia becoming Indonesia's top trending topic on Twitter.
The blunder came to light at Saturday's opening ceremony in Kuala Lumpur, where the souvenir magazine was handed out to dignitaries -- including Indonesia's Sports Minister Imam Nahrawi, who tweeted a picture of the offending page.
Indonesia's flag has a red stripe above a white stripe, but it was printed with the white stripe on top, making it look like the flag of Poland.
Malaysian organisers were quick to apologise and the country's Sports Minister Khairy Jamaluddin visited Nahrawi at his hotel to explain in person.
But it was not the only incident, as a SEA Games booklet also mixed up Indonesia and Thailand's flags in a reprint of the medals table from 2011.
A Malaysian daily newspaper also printed Indonesia's flag upside-down, while Games organisers were caught using the wrong flag for two Brunei athletes at the synchronised swimming.
The swimmers, Jacqueline Lim and Nur Hafizah Ahmad, were shown next to what appeared to be a flag for Brunei's armed forces, rather than the national emblem.
SEA Games organisers told Indonesia they "very much regret the mistake" and the foreign ministry also said sorry for the "inadvertent error".
"We would like to extend our apology to the government and the people of the Republic of Indonesia," the foreign ministry statement said.
"In this regard, we wish to assure the government of the Republic of Indonesia that all measures have been taken to address this unfortunate situation."
- 'National pride' -
The incident grabbed attention on the first full day of action at the biennial SEA Games, which mix Olympic sports with Asian favourites like pencak silat and wushu.
Indonesia's President Joko Widodo said it was a matter of "national pride" for the country, which is the biggest in Southeast Asia with about 260 million people.
"We deeply regret the incident but do not exaggerate it," he said. "We are waiting for the apology from the Malaysian government because this concerns the national pride of our country."
Indonesia's Olympic committee chief, Inter Milan president Erick Thohir, earlier criticised Malaysia's "negligence".
"Of course, I am expressing my deep regret on this fault, which shows negligence and absent-mindedness," he said in a statement.
"Friendship is the greatest legacy in sports, but a mistake in presenting a national identity of a nation is not justified."
Malaysia's SEA Games organisers are not alone in making mistakes with competitors' flags -- and receiving strong complaints afterwards.
Last year at the Rio Olympics, China complained bitterly that the flag used at medal ceremonies had its small gold stars pointing at the wrong angle.
At the 2012 Olympics North Korea's women's footballers refused to play, delaying the start of their game with Colombia, when they were shown next to the South Korean flag on a stadium screen.