Yadav became the fifth bowler to be reported by the tournament's match officials following Lahore Lions pair Mohammad Hafeez and Adnan Rasool, Dolphins Prenelan Subrayen and Kolkata team-mate Sunil Narine.
"After all video evidence of the match was taken into account, on-field umpires Rod Tucker and Kumar Dharmasena along with third umpire S. Ravi felt that there was a flex action in his elbow beyond the acceptable limit when bowling during the match," a statement from the CLT20 confirmed.
Yadav may now request an official assessment from the BCCI Suspect Bowling Action Committee.
Should he be reported again during a BCCI event while on its warning list, he would be suspended from bowling.
An occasional bowler, Yadav has taken six Twenty20 wickets in his career, bowling 132 balls in 40 matches for Kolkata and Mumbai Indians.
© Cricket World 2014