Two senior executives from Deutsche Bank are among 25 employees under investigation as part of a tax evasion probe into the bank's carbon trading business.

Deutsche Bank says its co-chief executive Juergen Fitschen and chief finance officer Stefan Krause are included because they signed the company's 2009 tax declaration.

Under the continent's widening emissions scam, fraudulent traders are alleged to have bought millions of carbon credits outside of Europe (thereby evading strictly monitored EU taxes on them) and then reselling them under the radar, while skimming the tax money off the top.

So far the police dragnet has included as many as 500 police officers raiding a number of bank-owned offices but also private properties in Frankfurt, Berlin and Dusseldorf.

The Frankfurt prosecutors' office said serious charges such as tax evasion, money laundering and attempted obstruction of justice are likely to be laid against some of the employees in question, but didn't cite the two executives specifically.

Deutsche Bank is just one of the banking names tied up in the investigation.

Fitschen and Krause's names were on some of the bank's tax declarations. In a statement, the bank said it is "co-operating fully" with the investigation.

With files from The Associated Press