Moldovan authorities say they have arrested six men suspected of smuggling uranium from Russia and trying to sell it to an unidentified buyer in a Muslim country in Africa.

Senior police investigator Vitalie Briceag said Wednesday the suspects were trying to sell a “few kilograms” of Uranium-235 that can be used to make nuclear weapons for nearly $29 million. He said the suspects had found a potential customer in the unnamed African country.

Briceag said the suspects were detained Monday and included four men from Moldova, a former Soviet state, as well as a Russian and a resident from Moldova's separatist Trans-Dniester region along the Ukraine border.

The investigator said Ukraine, German and U.S. authorities worked on the case and that the suspects had been followed since March. He said the small lead cylinder with the uranium was in the Moldovan capital Chisinau for a week and was found at one of the detained men's apartments.