"When the ruffian who vandalized Amar Jawan Memorial in Mumbai turned out to be a Bihari, the Bihar chief minister (Nitish Kumar) should have felt ashamed. Instead, he created a controversy when Mumbai Police went and nabbed the culprit," the party mouthpiece Saamna quoted Thackeray as saying.

"Anybody who comes here from Bihar and indulges in blatant crimes like daylight robberies, dacoities and murders, we shall not tolerate it," Thackeray warned.

He contended that if the Mumbai Police required prior permission of Bihar Police to nab criminals who commit crimes in Maharashtra and seek refuge in their home state, then a permit system must be implemented.

Thackeray declared that if Nitish Kumar, whose party is a constituent of the National Democratic Alliance, continued to support such "traitors", then the Shiv Sena would not accept him as a prime ministerial candidate.

Thackeray's statement came barely a week after his cousin and Maharashtra Navnirman Sena (MNS) chief Raj Thackeray also threatened to brand people from Bihar in Maharashtra as "infiltators" and succeeded in raising a hue and cry in Bihar.

He had also demanded a permit system for north-Indian migrants coming to Maharashtra for education or employment purposes.

The root of the sudden slanging match between the Bihar and Maharashtra politicians lay in the former Bihar chief secretary who had taken umbrage at a Mumbai Police team nabbing one of the culprits of the Azad Maidan violence Aug 11.

Earlier, Sena chief Bal Thackeray had also frowned on the Bihar government's attitude. "Nitish Kumar should have commended Mumbai Police for nabbing Abdul Qadir who could have created more trouble even in Bihar," the Sena patriarch had said.