KUALA LUMPUR: Police have quizzed four bank account holders whose particulars appeared in a ransom demand letter sent to City Hall over a threat to blow up the Kuala Lumpur City Centre (KLCC) Twin Towers. The four men who showed up on Saturday for questioning by police said they are puzzled how their names and bank account details were obtained by the sender of the letter, who is believed to be a local. Based on initial investigations, police are almost certain that the four are not involved in the threat. It is learnt that the sum demanded was RM20 million and not RM10 million as reported initially. Although police believe that those behind the threat were simply taking a "long shot for a quick buck", police are not taking it lightly, with the recent deadly terror attacks overseas. It is also learnt that police have advised the management of KLCC to beef up security and be watchful for suspicious movements. Officials of foreign embassies and consulates in the city have also raised their concerns with police after the case was highlighted in the media. Sources said police have investigated an address stated on the shipment slip of the letter that was sent by a courier company and it lead to a vacant shoplot in Kampung Pandan. On Thursday, Kuala Lumpur mayor Datuk Seri Ahmad Phesal Talib directed his officers to lodge a police report after the letter was delivered to his office. The sender threatened to bomb the KLCC Twin Towers unless the ransom is paid into the bank accounts of four individuals named in the letter. Ahmad Phesal was reported to have expressed his concerns over tourism in the city being affected by the case, which is being probed as criminal intimidation.