West Bengal Chief Minister Mamata Banerjee Wednesday alleged that the Criminal Bureau of Investigation (CBI) has become the BJP's policing agency.

"CBI has now become so called BBI (BJP Bureau of Investigation) - very unfortunate!" Banerjee tweeted.

The government has divested CBI Director Alok Verma and Special Director Rakesh Asthana of all powers amid the ongoing spat between them, sources said, calling it the first such case in the history of the agency.

The prime minister-led Appointments Committee Tuesday night gave charge of the director to Joint Director M Nageshwara Rao with immediate effect, a government order said.

According to the law, the CBI director is appointed for a fixed tenure of two years.

Earlier, Congress chief spokesperson Randeep Surjewala wondered if Verma was "sacked" for his keenness to probe the "layers of corruption" in the Rafale scam and sought an answer from Prime Minister Narendra Modi.

There was no immediate comment either from the government or the ruling BJP on the allegations levelled by opposition parties.

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