Carmakers across the globe have faced increased regulatory scrutiny over anti-pollution tests since Volkswagen AG (VOWG_p.DE) admitted in September 2015 to installing secret software allowing its cars to emit up to 40 times legally allowed pollution levels.
Daimler declined in its statement to elaborate on the raids, beyond saying it was cooperating with authorities.
The Stuttgart public prosecutor's office said 23 prosecutors and around 230 staff, including police and state criminal authorities, were involved in searching 11 sites in the German states of Baden-Wuerttemberg, Berlin, Lower Saxony and Saxony on the lookout for data files and evidence.
The searches were initiated in the course of investigations "against known and unknown employees at Daimler, who are suspected of fraud and misleading advertising connected to manipulated emissions treatment of diesel passenger cars," the Stuttgart prosecutor's office said.
It had said in March it had launched an investigation against employees at Daimler, which owns the Mercedes-Benz brand, on suspicion of fraud and misleading advertising.
In April, the Stuttgart-based carmaker warned that U.S. authorities had investigated diesel emissions pollution and so-called auxiliary emission control devices, which could lead to significant penalties and vehicle recalls.
Earlier this month, the German automaker dropped plans to seek U.S. approval to sell 2017 Mercedes-Benz diesel models.