As the Sri Lankan army continue its offensive deep into LTTE [Images] strongholds in the island nation's north, Tamil Nadu police have effectively 'strangulated' the Tigers' logistical routes by 'discreetly' clamping down on members of its logistics module to prevent the state from emerging as their 'procurement hub'.

Some of the top-rung members of the LTTE's procurement module, who had come to Chennai recently have been arrested and imprisoned, police sources told PTI in Chennai.

"This effort is going on in a discreet way and we have indeed stepped up our efforts against the organisation, which looks to procure material from Tamil Nadu, especially Chennai," a top police official said.

Arrests of these men have not been reported in the media since police did not want to disclose details, he said.

"Increased vigil on Rameswaram coast as well as in Chennai has resulted in more Tigers being nabbed and we are also keeping a close watch on the different refugee camps," the official said.

"A member of the LTTE is monitored from the moment he lands on Indian soil and is unaware that he is being tracked by the police. We allow him to wander for a while before catching him red-handed with the material as well as his contacts," they said.

The arrests include some senior members of the module. One accused, Thambi Annan, was nabbed after police followed him for a month to bust his contacts and recovered from him aluminium ingots and ball bearings, they said.

The crackdown has been intensified as the Tamil Tigers were locked in a battle to save their last strongholds in northern Sri Lanka [Images].