Sources say that the police have information about four sleeper modules infiltrating Hyderabad in the last four months.

However, it is difficult to crack down on these sleeper cells without any concrete information. 

According to Hyderabad Police Commissioner Balwinder Singh, it is difficult to nab members of these sleeper cells, as they can be arrested only if they are caught while committing an act of terror.

Police officials say that there is an immediate need to crack down on these sleeper cells as they may continue to strike at will.

A sleeper cell usually has at least four members and each member is assigned a particular task. Even though each member has a different task, they all work towards the same cause. For example, if one person has been assigned to collect materials to prepare a bomb, the others will be involved in assembling it.

According to sources in the Intelligence Bureau, the sleeper cells operating in Hyderabad may shift to Bangalore soon. The I-T capital of India is yet to witness a major terror attack.

In the wake of the recent terror attacks, the police force has become very vigilant in Andhra Pradesh, say sources. Hence, the sleeper cells may move to Bangalore to expand their activities.

However, IB sources in Karnataka indicate that there is no immediate threat to the state. The terror modules will refrain from terrorist activities in Karnataka, as these will draw the IB's attention towards the state.