The agency has sent a Letters Rogatory to Britain, official sources said.
The sleuths probing the allegations of corruption in Commonwealth Games have tracked an e-mail written by Patel to Organising Committee treasurer M Jaychandran which, they claim, confirms that kickbacks were paid to CWG Organising Committee Chief Suresh Kalmadi.
Patel's mail mentions details of money which was allegedly paid to Kalmadi and says that the dues should be cleared as swiftly as possible to his companies whose services were used during Queen's Baton Relay.
To corroborate the contents of mail, the CBI was trying to extract information from Patel but so far he has remained non-cooperative, the sources said.
Officials privy to the probe said they were trying to question Patel regarding his company's services extended during the ceremonies associated with the Queen's Baton Relay and alleged monetary exchanges involved in it.
The non-cooperation from Patel had prompted the agency to adopt a more rigorous legal path of sending Letter Rogatory to the United Kingdom in this regard.
Patel, who is accused in two cases involving the QBR, was allegedly paid 2.45 Lakh British Pounds for the services which was in violation of norms.
CBI said the first case was registered under different Sections of IPC and Prevention of Corruption Act in relation to the award of contract to London based AM Car and Van Hire Ltd at exorbitant rates.
The CBI had charged former OC Joint Director General T S Darbari, former Deputy Director General Sanjay Mahendroo, Director Raj Singh, Patel, and other unknown persons under relevant provisions of Indian Penal Code.
The agency has alleged that the accused officials of OC in conspiracy with the transport firm and its Director awarded work to the said firm at exorbitant rates without following the standard tender process.
The work was awarded on the false premise that the firm was on the panel of Indian High Commission, London. Two e-mails were allegedly forged by the officials of OC to justify the selection of the firm, the CBI has said.
The second case involves London-based A M Films, Patel, Mahendroo, Darbari and others in awarding the work of installation of video screens at the venue of QBR allegedly at exorbitant rates on the basis of fake quotations and without following standard procedure, it said.