But the Director-General of the World Health Organisation, Gro Harlem Brundtland, told the BBC that she could not rule out the possibility of a link, and said more research was needed.
Uranium-tipped ammunition has been blamed for cases of cancer among peacekeeping soldiers, Nato troops and civilians.
She gave no details, saying she would await the results of scientific studies being carried out by the European Union and several of its member countries.
Seven Italians, five Belgians, two Dutch nationals, two Spaniards, a Portuguese and a Czech national have died after serving in the Balkans. Four French soldiers have also contracted leukaemia.
"If coherent results emerge directly linking the use of depleted uranium ammunition with health problems suffered by soldiers and civilians, we will proceed immediately," Mrs del Ponte told the newspaper la Repubblica.
However, correspondents say it is doubtful that the tribunal could prosecute unless it emerged that depleted uranium had been deliberately used to cause cancer.
It would therefore be classed as a prohibited chemical weapon - rather than as a means of enhancing the amour-piercing performance of shells.
DU risks
Nato, which used depleted uranium weapons in the Balkans, insists there is no evidence linking their use with higher incidences of cancer and leukaemia.
But the Director-General of the World Health Organisation, Gro Harlem Brundtland, told the BBC that she could not rule out the possibility of a link, and said more research was needed.
On Sunday, Britain conceded that there was a "limited risk", but repeated that there was no proven link between DU and any illness.
But following the deaths from leukaemia of at least seven of its Balkan veterans, Italy has asked Nato to start an an investigation.
More research needed
Several other EU countries have also started their own inquiries, and the European Commission has set up a working group of medical and scientific experts that is due to report next month.
On Friday, the German Government said it could not establish a link between possible DU contamination and a blood related illness suffered by six German soldiers.
But a study commissioned by the German Ministry of Defence warned that steps should be taken to prevent potential danger to the local population, particularly children, who may play in areas where DU weapons exploded, releasing toxic chemicals.