German prosecutors and tax police have raided the offices of Deutsche Bank, Germany's biggest lender said on Wednesday.
"As part of an ongoing investigation against individuals suspected of tax fraud connected with trading in carbon emissions certificates, prosecutors searched the premises of Deutsche Bank in Frankfurt," a bank spokesman said.
"Deutsche Bank is cooperating fully with the authorities," he added.
According to Der Spiegel magazine in its online edition, at least 25 employees are suspected of evading hundreds of millions of euros (dollars) in tax and arrest warrants have been issued for five suspects.
The magazine said 500 officers also raided flats and offices in Berlin and Duesseldorf.
Prosecutors in Frankfurt were not immediately available to comment.
In December 2011, six businessmen -- three British citizens, two Germans and one Frenchman -- were sentenced to between three and seven years in prison for not paying taxes from trading in carbon emission certificates.
Investigations are still ongoing into other people who may have been involved.