* Prosecutors say raid relates to 210,000 diesel vehicles
* Probe focuses on emissions of 3-liter V6 diesel engines
* 14 people under suspicion regarding U.S. engine sales
* Audi says cooperating with prosecution (Adds further details from prosecutors' statement, background)
FRANKFURT, Feb 6 (Reuters) - German prosecutors searched offices at carmaker Audi's headquarters and its car plant in Neckarsulm, Germany on Tuesday in connection with the suspected manipulation of emissions on diesel vehicles, the Munich prosecutors' office said.
It said it also searched some private homes as part of its investigation, which relates to suspected fraud and illegal advertising in connection with the sale of at least around 210,000 vehicles in Europe and the United States since 2009.
"Now the focus of investigators is on the use of technical means to manipulate the emissions levels of 3-liter V6 diesel engines intended for the European market," the prosecutors' office said in a statement.
Regarding the investigation into the sale of Audi diesel engines in the United States, it said 14 people were now under suspicion, none of whom are former or current management board members.
Audi, the biggest contributor to parent Volkswagen's profit, admitted in November 2015 that its 3-liter V6 diesel engines were fitted with a device deemed illegal in the United States that allowed cars to evade U.S. emissions limits.
German prosecutors already searched its two biggest plants and other sites last March in connection with the emissions scandal.
Audi said on Tuesday it was cooperating with the prosecutors' office.
German daily Sueddeutsche Zeitung and broadcasters NDR and WDR first reported the searches by prosecutors. (Reporting by Maria Sheahan; Additional reporting by Irene Preisinger; Editing by Louise Heavens)