The Lalu Prasad-led party later clarified that the posters were not put up to belittle the chief minister, but criticise the government in the state.

The posters, bearing the signature and image of RJD leader Anand Yadav, who is said to be associated with the party's disaster management cell, were put up at the state headquarters in Birchand Patel Marg and in front of Tejashwi Yadav's official residence on Circular Road, a stone's throw away from the chief minister's house.

The posters were also inscribed with a slogan in Hindi, borrowing a verse from the Bhagavad Gita, "Whenever Ravana has committed atrocities, a Rama has incarnated".

The words 'Samvidhan Bachao Nyay Yatra' were displayed in bold font on the posters, which were an obvious appeal to the people to support Tejashwi Yadav on the next leg of his public interaction programme, scheduled to begin later this month.

The JD(U) reacted to the development with revulsion, with its spokesperson Rajiv Ranjan Prasad saying the RJD rule in Bihar was marked by lawlessness. Their disrespect for the state's chief minister was yet another reflection on its character, he said.

Asked whether the JD(U) would like the government to take any legal action against those involved in putting up the posters, Prasad told a news channel, "We do not attach much importance to the poster which deserves to be in dustbins. It is for the RJD to decide whether it wants to pursue its politics with the help of such unruly foot soldiers".

Asserting that Kumar, in his more than a decade-long tenure, has acquired "enormous goodwill", the JD(U) leader challenged the RJD to "get a referendum as to who is Ravana in the eyes of the people of Bihar and who is Rama". 

"The result will be sobering for the opposition party", Prasad said. 

The Congress, which has been an alliance partner of the RJD for more than two decades, also disapproved of the posters.

"This is not proper. No problem with Tejashwi being compared to Rama. But to depict anybody as Ravana is inappropriate. To call the chief minister a demon king is certainly not on," BPCC president Madan Mohan Jha and campaign committee chairman Akhilesh Prasad Singh told reporters.

RJD state spokesman Chitaranjan Gagan, however, said the poster was not part of the party's official publicity material.

"Our cadres are angered over Nitish Kumar's betrayal of mandate. Some of the over-enthusiastic ones gave vent to their frustration in this manner. Moreover, although Kumar has been shown as having 10 heads, the idea is not to insult him, but to criticise his government which has failed on all fronts ever since he ditched us and rejoined the BJP-led coalition," he said.