The complaint was submitted to the state police, demanding an enquiry and action in this regard.
In his complaint, Thomas said the alleged tapping was an intrusion into his privacy and demanded that the monitoring system in the cyber cell be enhanced.
A VACB source said information of some significant operations of the anti-corruption agency was suspected to have been leaked by tapping the telephones of higher-ups.
"The tapping of phone calls and hacking of email of top VACB officials is suspected," the source told PTI.
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The agency's decision to carry out raids at residences of former Excise minister K Babu and DySp Bijo Alexander, over complaints of disproportionate wealth, was suspected to have been leaked in this manner, the source added.
However, Behera told reporters in Malappuram that he was yet to receive any such complaint.
Behara said he had come to know about it through media reports and would take appropriate action on receiving it.
The complaint was 'serious' as it had been lodged by such a senior officer of DGP rank, he said.
The phone calls could be tapped only with the knowledge of the Home Department, held by the Chief Minister.This showed the government's trust deficit towards the official, he said.
Thomas had recently written to the Chief Minister,seeking his permission to relinquishing office, apparently annoyed over the re-surfacing of a report against him on financial irregularities when he was Ports director in 2013-14.
However, the ruling LDF, including leaders of the major parties CPI(M) and CPI wanted him to continue as the head of the anti-corruption agency.
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