Police in Thane registered a non-cognisable case for defamation against BJP national spokesperson Sambit Patra on a complaint alleging that he had posted on Twitter certain derogatory tweets, an official said on Tuesday.The complaint was lodged by Brijkishore Dutt at Mahatma Phule police station in Kalyan, said Thane Police PRO Sukhada Narkar.As per the complaint application, Dutt is general secretary of the Maharashtra Youth Congress.Police have filed a NC (non-cognisable) case under section 500 (Punishment for defamation) of the Indian Penal Code (IPC), another official said."In such cases, complainant can approach court against respondent," he explained.