"India is a mature democracy and the prime minister negotiates on behalf of the government. There is no question of withering away of the authority. The prime minister is fully authorised to carry on the negotiations," Mukherjee told reporters in New York after addressing the United Nations General Assembly on Wednesday.
The Pakistan President has said in his book 'In The Line of Fire' that the initial signs of sincerity and flexibility he sensed in Prime Minister Singh were "withering away".
"The initial signs of sincerity and flexibility that I sensed in Manmohan Singh seem to be withering away. I think the Indian establishment --the bureaucrats, diplomats and intelligence agencies and perhaps even the military—has gotten the better of him," Musharraf writes in the book.
Mukherjee also rejected the General's claim that India was defeated in the Kargil conflict.
"India had got back all its area in Kargil and also established its post there. So, there is no question of defeat," the defence minister said.
Casting doubts on various claims made by Musharraf in the book, Mukherjee said first Pakistan had said that only Mujahideen were involved (in Kargil conflict) but later admitted it was Pakistani army which was responsible for the incident.
"These statements were consistent with what Pakistan had also done in earlier conflicts, including in 1948, when first it denied any involvement of its army and claimed that either Mujahideen or tribals or indigenous insurgent were involved and then admitted it was the handiwork of its army," he said.
The minister said though he had not read the book, published reports show that there were so many inconsistencies with the statements made earlier and what has been written in the book that he would "leave it to the reader" to decide its authenticity.
Replying to a question, he dismissed the suggestion that six Pakistani battalions had pinned down four Indian divisions in Kargil as "absolutely incorrect."