The seizure came after a strong diplomatic protest by the US authorities to the Croatian President, Franjo Tudjman, and marks the first time in the Yugoslav conflict that weapons have been impounded in the country.
The shipment is the latest of several from Iran to Bosnia via Croatia. Its seizure has put Mr Tudjman in the awkward position of notifying the UN sanctions committee that Zagreb has seized weapons, thereby alienating its Muslim and Croat allies in Bosnia who are desperate for weapons and ammunition.
The Bosnian government has complained that the arms embargo is unfair. The poorly armed defenders of Sarajevo, Goradze and Bihac are vastly outgunned by the Serbian side, armed by the former Yugoslav army.
Meanwhile, the UN last night officially blamed Bosnian government military forces for the deaths of two French soldiers on Tuesday night, and for three other attacks on UN troops in the past three months.
A statement from the United Nations Protection Force (Unprofor) in Zagreb - unprecedented in its frankness - said categorically that the aid convoy ambushed at Sarajevo airport on Tuesday, in which the soldiers were shot dead, was 'attacked by Bosnian government forces'.
For the first time, the UN acknowledged that the Italian relief aircraft which crashed over Croatian lines last Thursday, killing all four crew and halting Sarajevo relief flights, was shot down.
All the UN casualties were incurred while the organisation was trying to alleviate the suffering of the mainly Muslim population of Sarajevo.
The UN statement appeared to implicate the forces of Bosnia's Muslim President, Alija Izetbegovic, in the four attacks since
5 June, which caused 59 casualties, including eight deaths.
Ejup Ganic, a Muslim member of the Bosnian presidency, denied the Muslim-led Bosnian forces were responsible. 'Where the shooting against the convoy took place, aggressor forces (Serbs) were in a certain area and our people in another,' he said.
The Bosnian government was sharply condemned by many countries involved in UN operations in what was Yugoslavia. Malcolm Rifkind, Secretary of State for Defence, said the killings, if deliberate, were 'repulsive', and that UN troops in Bosnia must 'be able to defend themselves'. Cyrus Vance, the UN envoy, said the killings were 'cold-blooded murder'. France's Foreign Minister, Roland Dumas, called them 'an act of war'.
UN peace-keepers have the authority to fire back when attacked or to use force to carry out their mission, but are loath to do so because of the risk of being drawn into the conflict. UN officials privately accuse the Sarajevo government of staging incidents to trigger such involvement.
The entire relief effort has been jeopardised by the killings. International aid has been, above all, for Sarajevo, not for Serbian-held areas. But if Bosnian government forces are blamed for attacks on the UN, there will be little enthusiasm for aid efforts to continue.Reuse content