Samajwadi Party leader Amar Singh on Wednesday alleged the Congress and the Nationalist Congress Party of collusion with Raj Thackeray and sought to remind the Maharashtra Navnirman Sena president that Bollywood star Amitabh Bachchan [Images] had made immense contribution to Maharashtra.

"Though the United Progessive Alliance government is at the Centre and the Congress/NCP regime ruling is Maharashtra, no action was taken so far, clearly indicating the Congress and the NCP's collusion with Raj Thackeray to thwart the progress of a third force (political alternative)," Amar Singh told reporters in Ranchi.

"Soon after Raj Thackeray's henchmen abused me at a recent press conference in Mumbai before the full media glare, I lodged an FIR in Marathi. But instead of taking action, we found Raj Thackeray participating in a private dinner invited by a top police officer,"  he said.

Supporting Amar Singh, Samajwadi Party president Mulayam Singh Yadav expressed regret over the UPA leadership not "bothering to enquire" about the incident.

"Even for courtesy neither the prime minister nor the Maharashtra chief minister considered it proper to make a telephone call to Amar Singh," Yadav said.

Both Yadav and Amar Singh were in Ranchi along with Telugu Desam Party president Chandrababu Naidu [Images] and All India National Lok Dal chief Om Prakash Chautala to attend a rally organised by the Jharkhand Vikas Morcha (Democratic) of former Jharkhand chief minister Babulal Marandi.