FRANKFURT, Germany (AP) -- Deutsche Bank (DB -0.12%) says its co-chief executive Juergen Fitschen and chief finance officer Stefan Krause are under investigation as part of a tax evasion probe linked to the bank's emissions trading business.

The bank said Wednesday Fitschen and Krause are being investigated because they signed off on the company's 2009 tax declaration. The bank says any errors in the declaration were corrected later in a timely way, adding that prosecutors say the changes were made too late.

Prosecutors said 500 police officers swooped in Wednesday on Deutsche Bank AG offices and private properties in Frankfurt, Berlin, and Duesseldorf.

Fitschen took over as co-CEO along with Anshu Jain earlier this year; in 2009, he was the head of the company's regional businesses.

The Frankfurt prosecutors' office says 25 employees of the bank are suspected of serious tax evasion, money laundering and attempted obstruction of justice. Arrest warrants have been issued against five, but those do not include Fitschen and Krause, a prosecutor's spokesman said.

Deutsche Bank said the investigation began in spring 2010 and focuses on "a limited number of individuals" under suspicion of fraud connected with value-added tax in the trading of carbon emission certificates.

It said it was cooperating with the investigation. The bank also faces lawsuits over alleged participation by former employees in rigging benchmark interest rates such as Libor along with other major banks, and has said it has put aside money for potential penalties in the matter.

Carbon trading schemes cap the emissions of businesses and set limits for countries. Businesses must buy carbon permits if they exceed their limit, or can sell the right to emit carbon if their emissions are lower. The idea is to limit the emission of greenhouse gases such as carbon dioxide that are believed to cause global warming.