Mumbai, Dec 13 (Reporter) The city police have heightened their vigilance along with other security agencies who are also on high alert after the head office of Reserve Bank of India (RBI) received another bomb threat via an alleged email. Security measures at RBI offices and its surrounding areas have been intensified to mitigate any potential risks, an official said here on Friday. The mail which was in Russian language was sent on Thursday afternoon to the RBI's official website. This is second such incident in less than a month. Last month on November 16, a bomb threat was made through the RBI's customer care number. In that instance, the caller claimed to be the 'CEO of Lashkar-e-Taiba', the terror group responsible for the 2008 Mumbai terror attacks. Adding a bizarre twist, the caller reportedly sang a song before issuing the threat. The Mumbai Police have registered a case against the unknown sender at Mata Ramabai Ambedkar (MRA) Marg Police Station. Officials confirmed that efforts are underway to trace the sender, who remains at large...////...