'The United States of America and the Kosovo Liberation Army stand for the same human values and principles ... Fighting for the KLA is fighting for human rights and American values." So declared the neocon US senator (and current foe of WikiLeaks) Joseph Lieberman back in 1999 at the height of the US-led military intervention against Slobodan Miloševic's Yugoslavia.

It would be interesting to hear what Senator Lieberman makes of the report of the Council of Europe – Europe's premier human rights watchdog – on his favourite band of freedom fighters. The report, which cites FBI and other intelligence sources, details horrific rights abuses it claims have been carried out by the KLA, the west's allies in the war against Yugoslavia 11 years ago.

The council claims that civilians – Serbian and non-KLA-supporting Kosovan Albanians detained by the KLA in the 1999 hostilities – were shot in northern Albania and their kidneys extracted and sold on the black market. It names Hashim Thaçi, the former leader of the KLA and Kosovo's prime minister, as the boss of a "mafia-like" group engaged in criminal activity – including heroin trading – since before the 1999 war. The report is a damning indictment not only of the KLA but also of western policy. And it also gives lie to the fiction that Nato's war with Yugoslavia was, in Tony Blair's words, "a battle between good and evil; between civilisation and barbarity; between democracy and dictatorship".

It was a fiction many on the liberal left bought into. In 1999 Blair was seen not as a duplicitous warmonger in hock to the US but as an ethical leader taking a stand against ethnic cleansing. But if the west had wanted to act morally in the Balkans and to protect the people in Kosovo there were solutions other than war with the Serbs, and options other than backing the KLA – the most violent group in Kosovan politics. They could have backed genuine multi-party negotiations, or offered to lift sanctions on Belgrade if a peaceful solution to the problem of Kosovo could be found.

Instead, a virulently anti-Serb stance led the west into taking ever more extreme positions, and siding with an organisation which even Robert Gelbard, President Clinton's special envoy to Kosovo, described as "without any question, a terrorist group". In 2000 the Sunday Times revealed that, prior to the Nato bombing, US agents had been training the KLA. Shaban Shala, a KLA commander, claimed he had met British and US agents in north Albania in 1996.

It was the KLA's campaign of violence against Yugoslav state officials, Serbian and Kosovan civilians in 1998, which led to an escalation of the conflict with the government in Belgrade, with atrocities committed on both sides. We were told the outbreak of war in March 1999 with Nato was the Serbian government's fault, yet Lord Gilbert, the UK defence minister, admitted "the terms put to Miloševic at Rambouillet [the international conference preceding the war] were absolutely intolerable … it was quite deliberate".

The subsequent 78-day "humanitarian" bombardment of federal Yugoslavia massively intensified the ethnic cleansing of Kosovan Albanians by Yugoslav forces. Between 2,000 and 10,000 Kosovan Albanians were killed by these forces, with between 500 and 1,500 people killed by the Nato bombing.

But even after Russian pressure forced a Yugoslav withdrawal from Kosovo, ethnic cleansing and rights abuses in the region continued. Under the Nato occupation an estimated 200,000 ethnic Serbs, Roma and other minorities from south Kosovo, and almost the whole Serb population of Pristina, have been forced from their homes.

A report on Kosovo by Minority Rights Group International claimed: "Nowhere [in Europe] is there such a level of fear for so many minorities that they will be harassed or attacked, simply for who they are." And in October 2010, a report by Human Rights Watch stated that "Roma and related minority groups deported from western Europe to Kosovo face discrimination and severe deprivation amounting to human rights abuse". As for democratic advances, Sunday's elections in Kosovo, boycotted by the Serbian minority, have seen widespread allegations of fraud, with a turnout of 149% reported in one area.

Far from being Tony Blair's "good war", Nato's assault on Yugoslavia was in its own way as immoral as the assault on Iraq. But as the Iraq war has become discredited, so it is even more important for the supporters of "liberal interventionism" to promote the line that Kosovo was in some way a success. The Council of Europe's report on the KLA's crimes makes that position much harder to maintain. And if it plays its part in making people more sceptical about any future western "liberal interventions", it is to be warmly welcomed.