Serbia's European Union membership bid is in further doubt after the funeral of convicted Bosnian Serb wartime commander Ratko Mladic, with EU Enlargement Commissioner Marta Kos saying Brussels must assess whether Belgrade remains committed to joining the bloc.

"Serbia is now at a turning point," Kos told Germany's Frankfurter Allgemeine Zeitung in an interview published on September 10, saying Serbia's accession process required it to confront its past, strengthen the rule of law and clarify its strategic orientation.

"We need to check to what extent Serbia is still honest about its European path," she said.

Kos said she would first discuss the issue with European Commission President Ursula von der Leyen. A report on the EU's readiness for new members is due at the end of September and could provide a basis for discussions among EU governments in October, she said.

The comments followed Mladic's funeral in Belgrade, which was attended by about 16,000 people. Mladic died on August 27 aged 84 while serving a life sentence in The Hague after being convicted of genocide over the 1995 Srebrenica massacre and other crimes committed during Bosnia's 1992-95 war.

European Commission President Ursula von der Leyen said on September 8 that images from the funeral were "shocking", particularly the presence of senior Serbian officials.

President Aleksandar Vucic did not attend, instead hosting an Uzbek delegation, but his son Danilo was present alongside Defence Minister Bratislav Gasic and Justice Minister Nenad Vujic.

Vujic said Mladic had received military honours at his family's request and that the state had only provided security.

Mladic's remains were returned to Serbia aboard a Serbian government plane and his coffin was carried by Serbian soldiers. His funeral service at Belgrade's Topcider cemetery was conducted by Serbian Orthodox Patriarch Porfirije.

Kos cancelled a planned visit to Belgrade over the funeral, asking: "How can you celebrate someone who has been convicted as a war criminal?"

She said she could not have travelled to Belgrade after seeing the public glorification of Mladic, given the suffering of the victims of the Srebrenica massacre.

Serbia's accession process was already stalled before the funeral. It has opened no new negotiating cluster since 2021, and eight EU member states blocked the opening of Cluster 3 in July. The cluster covers competitiveness and inclusive growth.

EU governments have cited concerns over the rule of law, Serbia's alignment with EU foreign policy and its refusal to align with EU sanctions against Russia. Serbia has refused to impose sanctions on Russia, given its heavy dependence on Russian gas, as well as its own experience of Western sanctions in the 1990s.

Kos said she remained ready to do everything possible to keep Serbia on the European path, but added that the outcome was also in the hands of Serbian politicians and voters, with parliamentary elections approaching.

Her comments amounted to an unusually direct appeal to Serbian voters ahead of the election and are likely to further strain relations with President Vucic, whose ties with Kos are already fraught.

She also rejected proposals for Serbia to join the EU under special arrangements that would give it different rights or obligations from existing members, saying EU treaties did not provide for "second-class" membership.

Vucic and Albanian Prime Minister Edi Rama recently proposed a form of staged accession that would give candidate countries earlier access to parts of the EU, such as the single market, before full membership with voting rights.