Dayanidhi Maran will be questioned soon by CBI in connection with his alleged role in coercing former Aircel Chief C Sivasankaran to sell his stake to a Malaysia-based group, agency sources said today.

Maran, who resigned as Textile Minister today, will be quizzed on the allegations levelled by Sivasankaran and spectrum policy changes made during his tenure during UPA-I, the sources said.

A Preliminary Enquiry on the issue of spectrum allocation during the period 2001-07 which spans across three telecom ministers -- Pramod Mahajan, Arun Shourie and Dayanidhi Maran-- is already underway, they said.

The agency is examining financial transactions of Sun TV, owned by Maran family, and Malaysia-based Maxis. It is also looking into various aspects of takeover of Aircel by Maxis group, they said.

According to the laid down procedure, CBI registers a PE upon receiving a complaint and when anything substantial is discovered this enquiry is converted into a regular case.

Former telecom minister Arun Shourie, who held the charge between 2003-04, has already been questioned by the CBI on February 25 about the allocation of telecom airwaves during his tenure but the agency so far has not found anything against him, they said.

The agency has registered a PE against "unknown persons" on Supreme Court''s directive to probe whether there was any anomaly in 'first-come-first-served' policy for spectrum allocation.