Khan targeted Tejashwi Yadav, younger son of Lalu Prasad, ahead of a review meeting to discuss the election outcome in which the once ruling Rashtriya Janata Dal (RJD) failed to win even one seat in the state.
"Tejashwi lacked experience to lead and manage politics. It was very much visible during the Lok Sabha elections. This badly affected the performance of the Grand Alliance," said Khan, a Congress legislator from Kadwa and a former JNUSU President.
Khan said that Tejashwi Yadav has no control over his language when addressing people.
"Tejashwi does not know when to say what and what not to say. It is a bad sign for a political leader leading an alliance in the state."
Khan said the feud in Lalu Prasad's family did not go down well with the people.
Lalu Prasad's elder son Tej Pratap Yadav was engaged in an open fight with Tejashwi Yadav during the election campaign.
Khan is the first Congress leader to publicly attack Tejashwi Yadav.
Senior RJD leader and former Union Minister Raghuvansh Prasad Singh on Tuesday blamed the feud between Lalu Prasad's two sons for the party's worst ever performance in the Lok Sabha battle.
Singh, who was himself defeated from Vaishali, has advised both the sons to introspect.
Three days ago, a RJD legislator, Maheshwar Yadav, demanded that Bihar opposition leader Tejashwi Yadav should resign on moral grounds after the RJD-led Grand Alliance was routed by the NDA in the Lok Sabha polls.
( With inputs from IANS )