State prosecutors in Bochum said around 270 tax officials searched the bank's headquarters and branches across Germany, looking into the sale of wealth management products "disguised" as tax-efficient life insurance policies.

"The aim was to enable clients to avoid tax on investment income," the prosecutors said in a statement.

The raids are the latest in a series by German prosecutors investigating tax evasion.

In November last year, Unicredit unit HVB and the German unit of Swiss lender UBS were searched.

Germany's largest bank Deutsche Bank was also the subject of raids one year ago as part of an investigation into tax evasion, money laundering and obstruction of justice linked to trade in carbon permits.

Commerzbank said on Tuesday that its offices were searched as part of the investigation and said it was cooperating fully with authorities.

"The investigations are not directed at the bank but at individual employees at another financial services provider," a Commerzbank spokesman said, declining to give further detail.

Bochum prosecutors did not identify the insurer involved but said in a statement they were investigating more than 200 instances beginning in 2006 when staff of the life insurer were suspected of having helped clients avoid German taxes.

German financial daily Handelsblatt cited industry sources as saying on Tuesday that the probe was focused on Italy's Generali and that investigators expected to find evidence of tax evasion in the hundreds of millions of euros.

Generali said in a statement it was aware of the media report but said it had not been notified of any tax probe.

"We confirm that neither Generali Pan Europe nor any other entity in the Generali Group has received any notification by any authority relating to these reported allegations," Generali said.

Commerzbank's private banking business had a close partnership with Generali's "Pan Europe" platform, which is based in Ireland and offers cross-border insurance and wealth management products to European clients.

A Commerzbank spokesman said the bank's cooperation with Generali ended in 2010 following Commerzbank's merger with rival Dresdner Bank.

Handelsblatt said the investigation centered around products known as insurance wrappers that were sold by Generali Pan Europe.

Insurance wrappers are life insurance policies into which the very wealthy place stocks, private equity holdings and other bankable assets, exploiting tax benefits on investment income held in such policies.

Wrappers are similar to trusts, which have a different legal framework, but can be set up and terminated more easily.

(Additional reporting by Alexander Huebner in Frankfurt and Lisa Jucca in Milan; Editing by Jane Merriman and Tom Pfeiffer)

By Jonathan Gould and Andreas Kröner

Stocks treated in this article : Assicurazioni Generali SpA, Commerzbank AG