Tarun Gogoi alleged it was a "political" decision as he often criticises the Narendra Modi government.
The centre has decided to withdraw the NSG cover of former Assam Chief Minister Tarun Gogoi and include incumbent Sarbananda Sonowal in the category.
Mr Gogoi alleged it was a "political" decision as he often criticises the Narendra Modi government for its "anti-people policies".
The decision to withdraw NSG security cover to Mr Gogoi was taken after a review meeting held on Wednesday, official sources said.
The NSG has informed Mr Gogoi about the decision and the state government will be communicated in due course of time, the sources said.
They said the NSG cover was meant for the chief minister of the sensitive northeastern state and since Mr Gogoi lost power, it would be extended to the incumbent in view of the threat perception.
Assam Police will be asked to look after Mr Gogoi's security as per requirement, the sources said, adding the veteran Congress leader will no longer be on the central list of protectees.
The NSG is, however, yet to take over the security of Mr Sonowal.
"Last night I received a communication from the Union Home Ministry about withdrawal of National Security Guards personnel. No reason was mentioned. The letter was forwarded to me by the Chief Minister's Office," Mr Gogoi told PTI in Guwahati.
He said when he contacted the DGP and the Additional DGP (Special Branch), they were not aware of the development.
"As per rule, a feedback goes from the state government.
But the government is saying it does not know. How can it be possible that the intimation was forwarded by the CM Office and nobody knows about it?" Mr Gogoi asked.
He, however, said the commandos were still with him as they have not got any further orders.
"I have never seen in my life that security cover was withdrawn from a former chief minister within just six months of demitting office.
"I am constantly criticising the anti-people policies of the Modi government and the BJP-led government in the state.
That is the only reason for withdrawing my security. Except politics, I don't see anything," he said.
He cited example of another former chief minister Prafulla Kumar Mahanta, who also enjoys security by NSG personnel.
"I was CM for 15 years and the UPA was in power for 10 years. We never did this to Prafulla Mahanta and he still enjoys the NSG security... Everybody knows how I controlled insurgency or jehadi problems in the state. How is it that till yesterday, I had threat and today not?" Mr Gogoi said.
Asked if he will appeal for a review, he said he will take a decision in a day or two.