In only slightly veiled criticism of the campaign, Mrs Robinson questioned the use of missiles to attack targets where there was a risk of killing innocent people.
Visiting the Macedonian capital of Skopje, she said: "If civilian casualties can be avoided, they obviously must be and it is down to judgements that must be made... If it is not possible to ascertain whether civilian buses are on bridges, should those bridges be blown?
"These are very important questions, because people are not collateral damage, they are people who are killed, injured, whose lives are destroyed, and we are very concerned about the way civilians are so much in the forefront of modern warfare, of modern conflicts."
Mrs Robinson's warning comes in the wake of the bombing of buses near Pec and Pristina, both in Kosovo, on Saturday and Monday. Nato accepts responsibility for the first but not the second. Mrs Robinson said Nato would be expected to observe the principles of legality and proportionality in its offensive.
"The question of how the principle [of proportionality] is to operate is a matter of judgement, and it is a difficult judgement, but in the context of civilian lives there should not only be a recognition of the need to adhere to the principle, but to err on the side of it in order not to cause civilian death, civilian injury or undue civilian suffering by being deprived of water, electricity, or lifesaving machines in hospitals."
The UN Security Council has asked for a report from Kofi Annan, the secretary- general, on the subject of civilians in armed conflicts. During her three- day visit, Mrs Robinson said she had heard accounts of "flagrant, savage violations" of human rights in Kosovo. She said the human rights community was working with the International War Crimes Tribunal in The Hague to ensure war criminals would be prosecuted.
Mrs Robinson was to have met Zorin Janackovic, the Yugoslav ambassador to Macedonia, yesterday, but the meeting was cancelled. She gave no explanation for this, but said she had asked Belgrade for permission to visit Kosovo.Reuse content