The CPI has demanded a CBI probe into the role of P Chidambaram in the 2-G spectrum issue. A party release issued in New Delhi today said that 2-G is a national issue and not an internal affair of the Congress party or the UPA. The CPI also pointed out that the CBI cannot decide or argue that it will not investigate Chidambaram's role as the then Finance Minister in the 2-G issue saying that the latest revelations warrant a probe.