Kolkata, July 4 : After a trespasser entered the official residence of West Bengal Chief Minister Mamata Banerjee on Saturday evening, Kolkata Police has decided to thoroughly overhaul the security arrangements there. City police commissioner, Vineet Kumar Goyal called a special meeting of top police officials where it was decided that the security assignment in and outside the chief minister's residence at Kalighat in South Kolkata will be divided among specialized units of the city police namely Special Branch (SB) and Special Task Force (STF). "The STF sleuths are specially trained for combating the anti-terrorist activities in the state. However, considering the gravity of the situation, a section of the STF sleuths will now be dedicated for the chief minister's security," said a senior city police official who refused to be named. He said that from now onwards there will be a three-tier security cordon in and around the CM's residence. The inner ring, which is inside the residence as well as its immediate surroundings will be manned by a joint team of plain-cloth SB officers and uniformed reserve force (RF) personnel. The second ring, which will be the main road and lanes leading to the chief minister's residence will be manned by the STF sleuths. The security arrangements in the third and outer ring will be manned by a joint team of local Kalighat police station and RF personnel. Refusing to divulge the details, joint Commissioner of Police (crime) of Kolkata Police, Muralidhar Sharma said that special arrangements are being made to beef up security at the chief minister's residence. Incidentally, even after 24 hours have passed since the trespasser was nabbed the city police is yet to disclose the identity of the person or spell out the motive behind his hiding at the CM's residence. That precisely has prompted opposition leaders in the state to throw subtle jibes about the incident. The CPI-M central committee member and the former leader of Left legislative parties in West Bengal assembly, Sujan Chakraborty said it is surprising that whenever the chief minister is in a politically difficult situation, some or the other issues relating to her security erupts. "There should be proper investigation in the matter on how a trespasser could get into such a high security zone," he said. Veteran MP and state Congress president in West Bengal, Adhir Ranjan Chowdhury said that the event shows the level the state police efficiency has come down during the last few years. BJP's national vice president and party MP, Dilip Ghosh said that probably the chief minister has something to hide at her residence and hence a lot of administrative movement had started over the event. /IANS