Speaking at a regular press briefing, Nikiforov recalled that the ICTY had the mandate to process only mass and systematic violations of the international humanitarian law, the Serbian news agency Beta reported.
There are no big and small crimes - a crime is a crime. But there is a difference in the scope of systematic and broad campaigns and individual incidents, Nikiforov said, stressing that this was why the ICTY had never investigated the events at Holmec.
The ICTY prosecution only has information that the case was dealt with by the Slovene authorities and does not want to comment on how it was done, he added.
The ICTY prosecution completed its investigations at the end of 2004, when the last indictments were issued, in line with a decision by the UN Security Council.
The killing of three conscripts of the former Yugoslav People's Army (JNA) carrying a white flag on 28 June 1991 in the battle for the Holmec border crossing, which also claimed the lives of some members of the Slovene Territorial Defence, was made topical again last week. The killing was recorded by the Austrian TV station ORF.
ICTY spokesman Christian Chartier confirmed at the press briefing that experts from Sweden last week completed a review of the management of the ICTY detention centre in Scheveningen and that they would submit their findings soon.
The review was prompted by the deaths of two indictees, Milan Babic and Slobodan Milosevic, on 5 and 11 March.
Chartier added that internal investigations into the two deaths were still under way.