Manmohan Singh can't reply to tweets: PMO

"PM of the country cannot reply to every tweet from leaders or press. We have to verify facts and make remarks," Communications Adviser to the PMO, Pankaj Pachauri, was quoted as saying by CNN-IBN.

"He is not a silent PM. He speaks when required," he added.

Earlier, former advisor to the Prime Minister, Sanjaya Baru, triggered a controversy by writing in his book 'The Accidental Prime Minister', that Singh surrendered to pressure from Congress president Sonia Gandhi and UPA allies.

In his book, Baru wrote that Singh was "defanged" by the Congress in his second term with Sonia, deciding over key appointments to the Cabinet and to the PMO.

Baru also wrote that Singh seemed to "surrender" to her and to the allies.

After Baru's book, another documentation called "Crusader or Conspirator? Coalgate and Other Truths" by former coal secretary PC Parakh, raised question on Singh's ability as a PM.

Speaking to media about his book, Parakh had said, "Unfortunately, the prime minister was not able to control his ministers and my suggestion on coal block auction was not accepted."

In his book, Parakh said that Singh, though keen to introduce open bidding, could not overcome resistances from coal ministers in his administration.