A purported telephone conversation between Lalu Prasad and Siwan don Mohammed Shahabuddin has triggered a political uproar with the BJP demanding criminal action against the RJD chief for speaking to the jailed gangster and "following his diktats".

In the telephone conversation, aired by Republic television news channel today, a man purported to be Shahabuddin is heard complaining to a person said to be Lalu against the Siwan superintendent of police and asking him to take action. A voice, apparently that of the RJD chief, is then heard asking an aide to connect him to the SP.

According to the TV channel, the conversation took place on April 15, 2016. Shahabuddin was on that date lodged in Siwan jail, serving out terms in several cases. He has since been shifted to Tihar jail in Delhi on the orders of the Supreme Court.

The audio clip indicates that Shahabuddin, a former four-time Lok Sabha member from Siwan, was unhappy over the manner in which the district police had handled the Ram Navami procession that day which had sparked sporadic clashes.

In the clip, he is heard telling Lalu that the Siwan police would trigger "communal violence" and asked him to get the SP removed.

The channel also aired other audio clips where Shahabuddin is heard telling a supporter that he will cut a block development officer to size - " aukaat mein le aayenge" - for impounding a vehicle owned by an aide of the don.

From New Delhi to Patna, the BJP went into an overdrive, asking chief minister Nitish Kumar to act against Lalu.

"On behalf of the BJP I want to ask Nitish Kumar, will he institute criminal proceedings against Lalu? The chief minister should break his silence and tell what action he will take," Union minister Ravi Shankar Prasad said at a news conference in Delhi.

In Patna, former deputy chief minister Sushil Kumar Modi, who has made a series of allegations of corruption against Lalu and his family over the past few weeks, said a criminal case should be started against the RJD boss. "Keeping constant contact with any jailed criminal or patronising any criminal are offences and Lalu did both. The Nitish Kumar government should register an FIR against him and take strict action," Sushil said and dared the state government to move court to cancel Lalu's bail in the fodder scam.

Chief minister Nitish Kumar remained silent on the issue though sources said he had summoned director-general of police P.K. Thakur to 1 Aney Marg this afternoon. No one in the chief minister's secretariat or the police headquarters would either confirm or deny the meeting.

The Janata Dal United was caught in a dilemma. Initially, industries minister Jai Kumar Singh declared that the episode required a probe. However, they clammed up following "instructions" not to speak on the issue. The Congress, the other partner in the Grand Alliance, too remained tight-lipped.

But JDU sources pointed out that even though Nitish has been accused by the BJP of acting under pressure from Lalu, the fact remains that none of the officers mentioned in the tapes have been removed or transferred since the purported call.

Saurabh Kumar Shah, a 2009 batch IPS officer, remains Siwan SP, a post he took charge of on August 3, 2015. Even the BDO remains in the same post.

"If nothing else, one should appreciate that Nitish Kumar does not buckle under pressure and the fact that the don's diktats are no longer obeyed in Siwan," said a JDU leader who did not wish to be named.

Sources said the file pertaining to relieve Sah for central deputation was pending with the chief minister. Sah is tipped to be appointed as the private secretary to a senior Union minister. The chief secretary and the home secretary are learnt to have given their approval for Sah's central deputation.

Lalu Prasad, who usually talks to media persons on a daily basis, had closed the gates of his 10 Circular Road residence.

Senior RJD leader Jagdanand Singh told reporters that Lalu had done nothing wrong in talking on the phone with Shahbuddin since the jailed don remains a leader of the party.

A delegation led by former state BJP president Mangal Pandey met Bihar governor Ram Nath Kovind at 5.30pm and submitted a memorandum appealing him to summon the director-general of police and issue instructions to register a case against Lalu.

No senior police official was willing to speak on the issue.