"In the context of a routine investigation of its own business, DaimlerChrysler has detected irregularities within its bus unit. This has led to the suspension of some executives, effective immediately," it said in a statement.
   
"In addition, Wolfgang Diez, CEO and President of EvoBus GmbH and head of DaimlerChrysler Buses, has resigned from his position today for personal reasons."

The company is already under investigation by the US securities and exchange commission over allegations that it used slush funds to bribe foreign officials.

US financial regulators and criminal investigators are also looking into potential violations of anti-corruption laws via payments that the company has said deal primarily with transactions involving government entities.
   
"DaimlerChrysler determined that improper payments were made in a number of jurisdictions, primarily in Africa, Asia and eastern Europe," it said in its 2005 annual report.
   
"These payments raise concerns under the US (anti-corruption law), German law, and the laws of other jurisdictions."
   
In addition, DaimlerChrysler has acknowledged possible tax liabilities for misclassifying or omitting commissions and other payments and expenses.

No one was immediately available at the company to comment on whether the suspensions arose from these investigations.

DaimlerChrysler shares were little changed after the news, up 0.5 per cent at 46.19 euros by 1522 GMT, while the DJ Stoxx European car sector index gained 0.8 per cent.