Three environmental activists from Russia were detained Tuesday after illegally demonstrating outside Parliament, officials said.
Two Russian citizens from a village damaged by radioactive contamination and an activist from the Moscow-based Ecodefense group came to Budapest to protest against the practice of dumping Hungarian nuclear waste in Russia, officials said.
Tuesday is the 19th anniversary of the Chernobyl disaster.
Spent nuclear fuel from Hungary's single nuclear plant in Paks was transported to the Russian village of Mayak until Russia's Supreme Court ruled the practice illegal in 1998.
Bilateral talks on resuming nuclear waste transport to Russia from Hungary were started last year prior to Hungary's accession to the European Union in May.
"We are here because we understand that Hungary and Russia have again started negotiations about the export of nuclear waste, though a law passed in 1998 stipulates that Russia would no longer receive harmful materials of any kind," Ecodefense activist Vladimir Slivyan told state news agency MTI.
The protesters also told MTI that they had learned from sources close to Russian ministries that a consignment of some 1,500 tons of nuclear waste from Paks would soon arrive in Muslinovo, their home village.
The two Russian citizens who suffer from radiation-related ailments brought "gifts" for Prime Minister Ferenc Gyurcsany from their village, including a bottle of contaminated water, a sack of contaminated soil and a reindeer antler equipped with an electronic gadget showing its radioactivity.
The Paks plant in southern Hungary provides around 40 percent of the country's electricity production.