Senior organized crime prosecutor Vitalie Busuioc said authorities knew of orders from two unnamed people to assassinate Vladimir Plahotniuc, an influential businessman and chairman of the Democratic Party, the biggest party in Moldova's pro-European governing coalition.
Police said the suspects had received USD 100,000 and were due to receive a total of USD 200,000.
Authorities detained eight people in Moldova and nine in Ukraine and seized an unspecified number of grenade launchers, two pistols, phones, wigs and moustaches.
Ukraine's Interior Minister Arseni Avakov on Friday said authorities had intercepted an assassination attempt against Plahotniuc.