Imran Sayeed and Mohammed Kaleem, the two accused in the twin blasts, had in their narco-analysis disclosed that they had helped obtain 50-100 SIM cards over a period of time. Hyderabad Police Commissioner admitted that these cards have still not been located and investigations are underway.

However, security agencies here are convinced that the Harkat-ul-Jehad-I-Islami (HUJI) has zeroed in on the mobile phone trigger mechanism to carry out such explosions.

It was used in the Mecca Masjid blasts and now in the Ajmer Sharif attack. Sources said the disclosures made by Saeed and Kaleem need to be taken “very seriously”.

Alerts have been sent across the country asking state governments to trace irregular and suspicious purchase of SIM cards.

HUJI is known to use largely two kinds of trigger mechanisms. The most favoured seems to be the mobile phone and the other is by using the common alarm clock which is what was found in the Hyderabad twin blasts and the Varanasi Sankatmochan explosions.

Obtaining a SIM card, sources said, is the critical part for terrorists and once that is available, this mechanism is perhaps the best option. Though mobile phones were not used in the twin blasts, the accused talked about SIM cards which, sources add, only emphasises the link.

“The basic issue is that SIM cards can be easily procured in large numbers over a period of time. It is a security hazard. We are now registering cases if anyone procures a SIM with a fake ID. What has been happening is that photocopies of older ID proofs are being to obtain new SIM cards. We are investigating this,” Hyderabad Police Commissioner Balwinder Singh told The Sunday Express.

Similar purchases were discovered in West Bengal, which is where the fictious name of Babulal Yadav first came to light. However, that was a case of six SIM cards. The prospect of over 50 cards out in the open is what has rung alarm bells here.