98 of the UN's 193 member nations recognise Kosovo's declaration of independence from Serbia, but Russia and China are among those who do not.
Russia interrupted a United Nations Security Council video conference to protest about the presence of Kosovo's flag.
It appeared behind Kosovo's foreign minister Donika Gervalla, bottom right in the picture, above.
Kosovo declared independence from Serbia in 2008, a decade after a brutal war between separatist ethnic Albanian rebels and Serb forces.
Currently, 98 of the UN's 193 member nations recognise Kosovo, including the vast majority of European Union members, but Russia, which has close ties to Serbia, and China are among the countries that have not.
Dmitry Polyansky, Russia's deputy UN ambassador, told the meeting: "The Russian Federation and most of the other members of the security council do not recognise Kosovo's independence, and the demonstration of the flag of that non-recognised entity is not acceptable,"
Polyansky added, however, that Russia did not object to allowing Gervalla to speak.
The request to ban the flag led to a 45-minute suspension of the virtual meeting while the council's 15 members discussed the issue in private.
The United Kingdom's legal counsellor Chanaka Wickremasinghe said council meetings are not formal and said Kosovo's flag had appeared behind its representative last time.
When the meeting finally resumed, the council's president, Vietnam's UN Ambassador Dang Dinh Quy, said the backgrounds of virtual meetings should not disrupt council sessions and the flag could stay.
But during his speech, Polyansky said the Kosovo representative had shown a "lack of respect" to a majority of Security Council members.
Gërvalla retorted that “the independence of the Republic of Kosova is a done deal. The earlier Serbia accept this reality the better it can get from its dark past into a bright future."
Nikola Selaković, Serbia's foreign affairs minister, said he had “no choice but to lodge a protest against the abuse of the video format of this session on the part of the representatives of Pristina in order to promote the symbols of the so-called statehood of Kosovo, despite the fact that the representatives of Pristina were warned on several occasions including by the president of the Security Council at the previous session that such abuses of the Security Council sessions are absolutely unacceptable.”