New Delhi, Jan. 11 -- The tussle between the Enforcement Directorate (ED) and the Trinamool Congress-led West Bengal government over controversial raids linked to political consultancy firm I-PAC reached the Supreme Court on Saturday, with both sides separately moving the top court amid mounting political and legal tensions in the poll-bound state. ED has filed a writ petition before the Supreme Court, alleging that its investigation was deliberately obstructed by the state machinery and chief minister Mamata Banerjee during search operations conducted in Kolkata on Thursday at the residence of I-PAC director Pratik Jain and the firm's office. The agency has sought directions for either a Central Bureau of Investigation (CBI) probe or an independent investigation into what it described as an unprecedented interference in a central agency's functioning. Anticipating ED's move, the West Bengal government on Saturday filed a caveat in the Supreme Court, requesting that no order be passed without hearing the state. A caveat is a formal legal intimation meant to ensure that the concerned party is heard before any interim relief is granted. According to people aware of the matter, ED is expected to urgently mention the matter before Chief Justice Surya Kant on January 12, contending that immediate judicial intervention is necessary to prevent destruction or tampering of evidence....