New Delhi - India Thursday criticized Pakistan for its "flip-flop" over the citizenship of sole surviving Mumbai attacker Ajmal Amir Qasab and its "recalcitrance" in failing to bring the perpetrators of the terrorist attacks to justice.

"He (Qasab) has told us quite categorically where he comes from, where he has received military and arms training from and where his handlers are located," India's Foreign Minister Pranab Mukherjee said in the southern city of Chennai.

"Unfortunately despite this we have seen a consistent flip-flop in the reaction of the government in Islamabad," he said.

India has long been insisting that the arrested gunman was a Pakistani and that the November 26 attacks were carried out by Pakistan-based Lashkar-e-Taiba.

Islamabad, which had been denying that the Mumbai attackers came from Pakistan, on Wednesday night admitted that Qasab was a Pakistani national.

However, the country's National Security Adviser Mehmud Ali Durrani was sacked from his post after he confirmed that Qasab was from Pakistan.

Over the past month, there have been several retractions from Pakistani officials and leaders in regard to the investigation of the terror attacks.

Former prime minister Nawaz Sharif, whose party governs Punjab province where Qasab lived, backtracked on his statement that the militant was a Pakistani.

Addressing a gathering in Chennai, Mukherjee said that more than a month after the Mumbai attacks, "there continues to be recalcitrance in bringing the perpetrators to justice."

Mukherjee said Islamabad was still in "denial mode," judging by statements of its officials rejecting evidence given by India.

Indian Prime Minister Manmohan Singh on Tuesday said the attacks had the support of some official agencies in Pakistan and the neighbouring country was using terrorism as an instrument of state policy.

Relations between the nuclear-armed neighbours have almost reached a nadir since the attacks in India's financial hub, in which at least 173 people including 26 foreign nationals were killed.

Speaking in Chennai, Singh said the forces of extremism and terrorism would not be allowed to destabilize the economy and polity of India. He promised to work with the global community to ensure that there are no safe havens or launching pads for terrorists.

Noting that the Mumbai attacks were a grim reminder of the threat posed by extremism to India's pluralistic and liberal traditions, Singh said, "There are some who would not like to see India succeed. But we have shown, over and over again, that we will not allow the forces of terrorism and extremism to destabilize our polity, our economy and our society," he said.

Amid the strain in India-Pakistan ties, Richard Boucher, US assistant secretary of state for south and central Asian affairs, was slated to hold talks with top Indian diplomats in Delhi.

Boucher was scheduled to meet India's Foreign Secretary, Shivshankar Menon later on Thursday and both sides were expected to discuss how Pakistan could cooperate in pursuing the leads into the terrorist attacks. (dpa)