Chernobyl was the scene of the world's worst civilian nuclear power disaster in 1986.
"The Ukrainian Security Service identified and put a stop to the unlawful activities of a criminal gang, which had been illegally removing from Chernobyl radioactive scrap metal, automobile spare parts and timber," the service said in a statement.
The statement said that the timber from Chernobyl was usually reprocessed at underground plants and later sold as construction materials, while the metal items were usually melted down for scrap.
The criminal gang also tried to take an old Mi-8 helicopter from the contaminated area for use as a themed cafe in one of Ukraine's cities.
Vast areas, mainly in the three then-Soviet republics of Ukraine, Belarus and Russia, were contaminated by the fallout of the Chernobyl NPP explosion. More than 300,000 people were relocated after the accident. However, 5 million people still live in areas of Belarus, Russia and Ukraine classified as "contaminated" by radiation.
There is no accurate data on the number of deaths, due to Soviet secrecy over the disaster. The Chernobyl Forum said 56 people, mainly rescue workers, were killed at the scene, and another 4,000 died of thyroid cancer shortly afterwards.