Croatia reacted angrily at verdicts pronounced by the UN war crimes tribunal in The Hague in the cases of three former Yugoslav Army officers.
The verdicts sparked Croat anger
Two of the defendants were sentenced for war crimes in the city of Vukovar in 1991 and the third was acquitted.
President Stipe Mesic called the verdicts "unacceptable".
The three were tried over the massacre of nearly 200 Croatian paramilitaries captured during the siege of Vukovar by Yugoslav troops and Serb forces.
Mr Mesic, who has been known as a supporter of the UN tribunal in the Hague, issue a stern condemnation of the verdict.
"The verdict in the trial of the so-called Vukovar Three is absolutely unacceptable both in terms of the duration of the sentences and the explanation of the verdicts," a presidential statement quoted by the Hina news agency says.
Anger in Vukovar
Former Yugoslav commander Mile Mrksic was sentenced to 20 years in prison for his role in the 1991 massacre of 194 people taken from a Vukovar hospital.
His subordinate officer, Veselin Sljivancanin, was sentenced to five years in prison for aiding and abetting torture, while a third accused, Miroslav Radic, was acquitted in the absence of evidence that he was aware of the killings.
They were convicted of war crimes, the tribunal accepting the claim that those killed were members of the Croatian paramilitary and not civilians, whose killing is considered a crime against humanity and incurs a heavier penalty.
Croatia disputes this ruling, saying those killed were civilians.
Croatian Prime Minister, Ivo Sanader, travelled to Vukovar on Thursday to appease a crowd angered by the verdicts.
"I am shocked by this ruling," said Benazija Kolesar, a nurse who was on duty in Vukovar hospital at the time of the massacre.
"They were responsible, they knew the wounded were taken from the hospital. There is no sentence high enough for these people." A paramedic in Vukovar hospital, Zarko Pavlovic, was equally upset.
"If you stole a car today you would get a harsher sentence than what they got for the biggest crime that was committed here in the past 50 years," he said.
Some 1,000 of the town's residents died during the fighting in November 1991 and another 5,000 were taken prisoner.
Croats regard the siege of Vukovar by the Serb-dominated Yugoslav Army as a key event in the war for independence.