Their leaders have paid their respects to the victims, begged forgiveness "on their knees," and deplored a "heinous crime," but Serbia and Serbs still stubbornly refuse to call the Srebrenica massacre a genocide, experts say.

International courts have ruled that the 1995 killing of nearly 8,000 Muslim men and boys in the ill-fated Bosnian town by Serb forces was genocide, "but here it is difficult to say that word," prominent independent political analyst Vladimir Goati said.

"Some even have a physical discomfort when it comes to saying it," he added.

Bosnian Serb forces captured the eastern town of Srebrenica on July 11, 1995, and over the following days massacred thousands in Europe's worst atrocity since World War II.

The killing came shortly before the end of Bosnia's 1992-1995 war between its Croats, Muslims and Serbs that claimed some 100,000 lives.

The massacre remains divisive at an international level even 20 years later -- on Tuesday the UN Security Council was forced to delay a vote on a draft resolution recognising what happened in Srebrenica as genocide after Russia threatened to veto the text.

And for Serbs, while a recent poll showed 54 percent do not question the crime's brutality, an overwhelming majority -- 70 percent of those asked -- still deny it was genocide.

Local politicians "only take into account public opinion so as to not lose voters and, without mentioning the word genocide, use descriptions that say the same thing," analyst Aleksandar Popov said.

In 2010, then Serbian president Boris Tadic went to Srebrenica to pay homage to the victims without saying the key word.

That same year the Serbian parliament adopted a resolution condemning the "crime committed against the Bosnian (Muslim) population in Srebrenica".

"I kneel and ask forgiveness for Serbia for the crime committed in Srebrenica," Tadic's successor Tomislav Nikolic said in 2013.

His contrition came a year after denying that a genocide was committed in Srebrenica, prompting outrage in the region and condemnation from Europe and the US.

- 'Hard to accept' -

Historian Cedomir Antic believes Belgrade's position is "understandable."

"To accept that genocide was committed would mean to accept an accusation of being a genocidal people," the Belgrade University historian told AFP.

"You are no longer there, nobody wants to negotiate with you, so Serbia cannot recognise that. Among other things, the existence of Republika Srpska would come into question."

He was referring to the Bosnian Serb entity, which along with the Muslim-Croat Federation has made up Bosnia since the end of the 1990s war. The two halves are semi-autonomous and are linked by loose central institutions.

Bosnian Muslims have demanded several times that Republika Srpska be dismantled, claiming it was founded on a genocide.

But for international legal expert Tibor Varadi the case is closed. He represented Serbia before the International Court of Justice (ICJ) when it was accused by Bosnia of being directly involved in the Srebrenica genocide.

"The International Court concluded in 2006 that Serbia had not committed genocide in Srebrenica and nothing can change that fact," he said.

Goati, the political analyst, said Serbia's reaction to calling Srebrenica a genocide is characteristic of any people or individual accused of an atrocity.

"Nations and individuals have a problem admitting or talking about events in which they played a negative role," he told AFP.

Serbian Prime Minister Aleksandar Vucic on Tuesday said he would attend the 20th anniversary commemoration of the Srebrenica massacre this weekend in a bid to forge reconciliation, but stopped short of using the controversial term.

"It is time to show that we are ready for reconciliation and that we are ready to bow our head before other peoples' victims," Vucic told reporters.

"That is why the Serbian government tonight decided that as prime minister, I would represent the Republic of Serbia in Srebrenica on July 11."

Vucic has said in the past that Serbs respected the "pain and suffering of others and even understand the hatred towards us from those who went through the hell of Srebrenica".

But the head of an association of women whose male relatives were killed in the massacre said Vucic's presence in Srebrenica would be a de facto recognition of the genocide.

"Something is awakening in the consciousness of the Serbian people. I believe that 20 years on it is difficult to live while denying what happened in Srebrenica," said Munira Subasic, head of the Mothers of Srebrenica group.