Klose crocked again, a day after recovering
The 32-year-old striker was injured during training with the reserve team on Wednesday and will miss his the champions' next few league matches as well as their Champions League clash at CFR Cluj next week.
"He was again diagnosed with a muscle injury in his left thigh, just as he had recovered from the injury in the same thigh," the club said in a statement.
Klose's absence is a further blow to the champions who are 11th in the Bundesliga after a poor start to the season.
Bayern are already without injured wingers Arjen Robben and Franck Ribery as well as captain Mark van Bommel and defender Diego Contento among others.
Striker Ivica Olic and defender Daniel van Buyten have recovered from their injuries and are expected to play in their league match against Freiburg on Friday.