World Cup 2011 final between India and Sri Lanka in Wankhede stadium in Mumbai today.
Not only calls made from residential numbers of bookies are on close surveillance but even their bank account is being closely monitored.
"Police are well-aware about the betting that will take place in the match today where crores of rupees will be placed. As a preventive measure, we had already traced the location from where the gang of bookies function and since two days we are surveilling their 25 mobile and residential phones," SP (City) Kushhar Saurabh said.
In addition to it, more than 100 mobile phones of suspected bookies were monitored and their activities were also closely followed, he asserted.
After the police came to know about the new SIM cards and phones being taken by the bookies, the police teams raided Govindnagar, Naubasta, Kakadev, Swarupnagar, Chakeri, Harbansh and various other places in the city last night.
Some of the bookies have switched off their mobile phones while some have taken new SIM-cards to make calls after they came to know that their phone calls were being traced by the police, the senior officer said.
In order to maintain peace in the city security is being tightened in sensitive areas to prevent any untoward incident after the end of the match, Saurabh said.