Moscow/Kiev - Customs formalities at the Russo-Ukrainian border have delayed a camel shipment for days and killed one animal, news agencies reported Tuesday.

The lorry-load of 19 surviving Bactrian (two-hump) camels had been en route from Russia's Caspian Sea autonomous republic Kalmykia to a Bulgarian zoo, only to be halted by Ukrainian border guards near the Russian city Rostov.

One camel died waiting as Russian and Ukrainian border officials wrangled for close to two weeks over the animals' further transit.

Stress reportedly killed the animal. Russian border troops unloaded the camels into a holding pen on Monday and were providing food and water, Russia's Interfax news agency reported.

"The greater portion of the camels are in shock. The animals are very aggressive," the lorry driver was reported in the Russian newspaper Komosomolskaya Pravda as saying.

The camels had not undergone international standard veterinary checks and posed a threat to Ukrainian livestock, particularly as possible carriers of African swine flu, Ukrainian officials cited by Korrespondent magazine stated.

Ukraine will allow the animals' transit if they were hauled in a special closed trailer, rather in the open cattle trailer they rode to the Ukrainian border from the Kalmykia steppe, according to the Komsomolskaya Pravda report.

Kirsan Iliumzhinov, Kalmykia's President, on Monday expressed "deep regret" a camel had lost its life en route to Bulgaria, according to the Lenta. Ru news service.

Temperatures at the camels' holding site, the Russo-Ukrainian border near the Russian city Rostov, have been relatively warm at a few degrees above freezing for the last week. (dpa)