MOSCOW, October 16 (RIA Novosti) - Swine fever, which has hit Russia's southern Rostov Region and the Republic of Kalmykia, could spread to three neighboring regions if no measures are taken, Russia's top veterinary inspector said on Friday.

African swine fever hit the Rostov Region in late September, and then spread to the neighboring Republic of Kalmykia.

Nikolai Vlasov told journalists "no effective administrative measures" have been taken in the region to stop the spread of the disease, adding the entire one-million pig population in the region could die as the result of local authorities' negligence.

"The virus will probably spread to the Belgorod Region, the Penza Region and the Republic of Mordovia," Vlasov said, adding if the spread of the disease is not stopped in these regions, swine fever could also affect the Tambov Region.

Besides the Rostov Region and the Republic of Kalmykia, African swine fever has been registered in five other regions in Russia's south, including North Ossetia, the republics of Chechnya and Ingushetia, and the Stavropol and Krasnodar territories.

Earlier in the day, Ukraine tightened border controls with Russia in order to prevent spreading of swine fever to its territory.

African swine fever, or Montgomery's disease, was first reported in Africa in 1903. Both domestic and wild animals can become infected when they come into contact with sick animals. The virus does not affect humans.