* 2nd Audi-related emissions raid since March 2017
* Number of accused in Audi probe up to 13 people
* Coincides with Stuttgart prosecutors raid on Bosch staff (Adds detail on accused people, background and Bosch raid)
BERLIN, Jan 31 (Reuters) - German prosecutors searched the homes of several current and former Audi employees on Wednesday in connection with the carmaker's involvement in parent Volkswagen's diesel emissions test-cheating scandal.
The raids, which follow searches at Audi's two German plants last March, were carried out at apartments in the western states of Bavaria, Baden-Wuerttemberg and Rhineland-Palatinate, prosecutors in Munich said.
The number of accused people involved in proceedings related to Volkswagen's luxury division rose to 13 in January from six, but still includes no current or former Audi executives, prosecutors said.
All defendants are under suspicion for possible criminal offenses in the United States where Volkswagen's (VW) emissions trickery was revealed in September 2015, they said. The raids were first reported by Germany's Sueddeutsche Zeitung daily.
Audi facilities were not searched, a spokesman at the carmaker's base in Ingolstadt said, adding it had learned about the raids through the media.
Audi, a key contributor to VW group profit, developed 3.0 liter V6 diesel engines equipped with illicit emissions-control software and used in about 80,000 VW, Audi and Porsche vehicles that were found to exceed U.S. emissions limits.
The Munich prosecutors' swoop coincided with similar action by their Stuttgart counterparts, who earlier on Wednesday said two employees of auto supplier Robert Bosch were being probed over Chrysler emissions in the United States. (Reporting by Andreas Cremer Editing by Emma Thomasson and Mark Potter)