Government sources said today that an urgent letter was sent following a request for the same by the investigating agencies including the CBI and Enforcement Directorate.

The sources said Union Home Secretary G K Pillai had written to both Mumbai Police Chief Arup Patnaik and Delhi Police Commissioner B K Gupta, asking them to provide security to the seven "witnesses" who had recorded their "confessional" statements under section 164 CrPC before a magistrate.

The move came amid reports that underworld gangs might try and target these witnesses to subvert the probe.

Sadhick Batcha(30), a close aide of former Union Telecom Minister A Raja, died in Chennai last month under mysterious circumstances while 30-year-old Deepak Pushpanathan, Raja's wife's cousin, died on Wednesday. Deepak was working with Etisalat DB, a firm under the scanner in connection with the 2G spectrum scam.

Batcha, who was quizzed by CBI regarding the 2G scam, was found dead at his home in south Chennai. His wife had claimed he committed suicide as he was unable to cope up with the pressure of the probe. The CBI has taken over the probe into the death of Batcha.

CBI and ED had conducted searches at Batcha's official and residential premises in December. He had been called for questioning four times since then.

CBI in its chargesheet filed on April 2 had alleged that the money connected with the 2G spectrum scam was routed through Batcha's company to Kalaignar TV Pvt Ltd in which Tamil Nadu Chief Minister M Karunanidhi's wife Dayaluammal was one of the owners.