Romanian prosecutors said Monday they had launched an investigation after the theft of 1.6 million carbon credits from the local branch of Holcim.
"A total of 1.6 million carbon credits, worth 24 million euros, have been transferred illegally," the Department Investigating Organised Crime and Terrorism (DIICOT) said in a statement.
About 600,000 credits have been recovered, a DIICOT spokeswoman told AFP.
Late November, Holcim informed authorities about "10 unauthorised transfers of polluting rights from two of its accounts opened at the national registry of carbon credits."
Romanian prosecutors have requested rogatory commissions in Italy, Britain, Liechtenstein, Belgium and Israel.
According to Romanian daily Gandul, the polluting rights were first transferred to Liechtenstein and then resold.
The EU on Thursday extended a halt on trading in carbon credits ordered after hackers broke into national trading registries and stole and then sold millions of euros worth of polluting rights.